As 3798-2007 Guidelines on Earthworks for Commercial and Residential Developments
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AS 3798—2007 3798—2007 (Incorporating Amendment No. 1) A S 3 7 9 8 — 2 0 0 7
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Australian Standard
®
Guidelines on earthworks for commercial and residential developments
This Australian Standard® Standard® was prepared by Committee CE-027, CE-027, Earthworks. It was approved on behalf of the Council of Standards Australia on 11 December 2006. This Standard was published on 12 March 2007.
The following are represented represented on Committee CE-027: • •
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• • • • • •
AUSTROADS Association of Consulting Consulting Engineers Australia Association of Geotechnical Geotechnical Testing Authorities Authorities (Qld) Australian Building Building Codes Board Australian Geomechanics Geomechanics Society Institute of Public Works Engineering Australia National Association of Testing Authorities Australia University of New South Wales
This Standard was issued in draft draft form for comment comment as DR 05390. Standards Australia wishes to acknowledge the participation of the expert individuals that contributed to the development of this Standard through their representation on the Committee and through the public comment period.
Australian Standards® are are living documents documents that reflect progress in in science, technology and and systems. To maintain their currency, all Standards are periodically reviewed, and new editions are published. Between editions, amendments may be issued. Standards may also be withdrawn. It is important that readers assure themselves they are using a current Standard, which should include any amendments that may have been published since the Standard was published. Detailed information about Australian Standards, drafts, amendments and new projects can be found by visiting Standards Australia welcomes suggestions for improvements, and encourages readers to notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at , or write to Standards Australia, GPO Box 476, Sydney, NSW 2001.
AS 3798—2007 3798—2007 (Incorporating Amendment No. 1)
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Australian Standard
®
Guidelines on earthworks for commercial and residential developments
Originated as AS 3798—1990. Third edition 2007. Reissued incorporating Amendment Amendment No. 1 (August 2008).
COPYRIGHT
© Standards Australia All rig hts are res erv ed. No part of thi s work may be rep rod uce d o r c opie d i n a ny for m o r b y any means, electronic or mechanical, including photocopying, without the written permission of the publisher. Published by Standards Australia GPO Box 476, Sydney, NSW 2001, Australia ISBN 0 7337 8096 2
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PREFACE This Standard was prepared by the Standards Australia Committee CE-027, Earthworks, to supersede AS 3798—1996. This Standard incorporates Amendment No. 1 (August 2008). The changes required by the Amendment are indi cated in the text by a marginal bar and amendment number against the clause, note, table, figure or part thereof affected. The objective of this Standard is to provide guidance to those responsible for or involved in the design, specification, supervision and control testing of earthworks for commercial and residential developments. . ) 1 2 1 3 5 0 0 1 (
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This Standard is a guideline, which is an informative document only. A1
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CONTENTS Page SECTION 1 SCOPE AND GENERAL 1.1 SCOPE ........................................................................................................................ 5 1.2 TERMS AND DEFINITIONS ..................................................................................... 5 1.3 DESIGNATION OF PERSONNEL............................................................................. 7 SECTION 2 INVESTIGATION, PLANNING AND DESIGN ................................................ 8 . ) 1 2 1 3 5 0 0 1 (
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SECTION 3 DOCUMENTATION 3.1 GENERAL ................................................................................................................ 12 3.2 INVESTIGATION AND PLANNING ...................................................................... 12 3.3 DESIGN AND SPECIFICATION ............................................................................. 12 3.4 CONSTRUCTION..................................................................................................... 13 3.5 SITE RECORDS ....................................................................................................... 14 SECTION 4 MATERIALS 4.1 GENERAL ................................................................................................................ 15 4.2 MATERIALS SOURCED ON SITE ......................................................................... 15 4.3 UNSUITABLE MATERIALS................................................................................... 15 4.4 SUITABLE MATERIALS......................................................................................... 16 SECTION 5 COMPACTION CRITERIA 5.1 GENERAL ................................................................................................................ 17 5.2 COMPACTION OF SOILS ....................................................................................... 17 5.3 PLACEMENT MOISTURE CONTENT ................................................................... 19 5.4 COARSE MATERIAL .............................................................................................. 19 5.5 TEST ROLLING ....................................................................................................... 20 5.6 OTHER MATERIALS .............................................................................................. 20 5.7 TRENCHES .............................................................................................................. 20 SECTION 6 CONSTRUCTION 6.1 SITE PREPARATION............................................................................................... 21 6.2 FILL CONSTRUCTION ........................................................................................... 23 SECTION 7 METHODS OF TESTING 7.1 GENERAL ................................................................................................................ 26 7.2 FIELD DENSITY ...................................................................................................... 26 7.3 ESTABLISHMENT OF A REFERENCE DENSITY FOR CALCULATION OF RELATIVE COMPACTION..................................................................................... 26 7.4 SAMPLE SELECTION FOR REFERENCE DENSITY............................................ 27 7.5 USE OF DIFFERENT TEST PROCEDURE ............................................................. 27 7.6 PERMISSIBLE OVERSIZE ...................................................................................... 27 7.7 PREPARATION OF LABORATORY REFERENCE DENSITY SAMPLES ........... 27 SECTION 8 INSPECTION AND TESTING 8.1 GENERAL ................................................................................................................ 29 8.2 LEVEL 1 INSPECTION AND TESTING ................................................................. 29 8.3 LEVEL 2 SAMPLING AND TESTING.................................................................... 29 8.4 GEOTECHNICAL INSPECTION AND TESTING AUTHORITY (GITA) .............. 30 8.5 GEOTECHNICAL TESTING AUTHORITY (GTA) ................................................ 30 8.6 STATEMENTS OF COMPLIANCE ......................................................................... 30 8.7 FREQUENCY OF TESTING .................................................................................... 30
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APPENDICES A REFERENCED DOCUMENTS ................................................................................ 32 B TYPICAL SITE RECORD SHEETS ......................................................................... 34 C STATISTICAL METHODS IN EARTHWORKS ..................................................... 40 D SUITABILITY OF COMPACTION EQUIPMENT FOR VARIOUS TYPES OF FILL MATERIALS ................................................................................................... 42
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AS 3798 —200 7
STANDARDS AUSTRALIA
Australian Standard Guidelines on earthworks for commercial and residential developments
S E C T I O N
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S C O P E
A N D
G E N E R A L
1.1 SCOPE . ) 1 2 1 3 5 0 0 1 (
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This Standard provides guidance on the specification, execution, and control testing of earthworks and associated site preparation works for commercial and residential developments. This Standard does not in itself constitute a specification for earthworks and the specifier should consider the applicability of these guidelines to the project under consideration. The Standard is not intended to be used for pavements, major roadworks, or water-retaining structures. Such works require special consideration. Residential developments in the context of this Standard are intended to include single lot development up to broad acre subdivisional development for detached or semi-detached housing. The Standard is not intended to be sufficient for medium- or high-density residential development without due consideration by a suitably qualified professional. Historically, previous editions of this Standard have been used to assist in the specification and execution of earthworks beyond the intended scope of the document. Whilst with due consideration some aspects of this Standard may be applicable to such works, designers and specification writers should be aware the guidance given herein may not be applicable. In such circumstances, appropriate advice should be sought from a suitably qualified professional before adopting this Standard. Where the depth of filling required for works to which this Standard would otherwise be applicable exceeds 5 m, advice from a geotechnical professional should be sought. 1.2 TERMS AND DEFINITIONS
For the purpose of this Standard, the definitions below apply. 1.2.1 Cohesionless soil
Poorly graded sand and gravel mixture, generally with less than 5% fines (i.e., particles finer than 75 µm diameter), which is non-plastic and which does not exhibit a well-defined moisture-density relationship when tested in accordance with AS 1289.5.1.1 or AS 1289.5.2.1. 1.2.2 Cohesive soil
Material that has a well-defined moisture-density relationship when tested in accordance with AS 1289.5.1.1 or AS 1289.5.2.1. NOTE : This may inc lude w ell -gr aded granular mat erials suc h as crushed rock.
1.2.3 Collapsing soil
Soil that may suffer a significant decrease in volume under load or when it becomes nearly saturated, which may have existed in this metastable state for a long period.
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1.2.4 Compaction
The process whereby the density of a soil mass is increased by mechanical, usually dynamic, means. This typically involves tamping, rolling, impact or vibration, or a combination of these processes. This process results in a relocation of the soil particles and in the expulsion of air from the soil mass, usually without significantly altering the amount of water in the soil. 1.2.5 Consolidation
The process by which water, and sometimes air, is expelled from a soil mass over time due to the action of an imposed static stress and causes settlement. NOTE : The term s compaction a nd consolidation are not int erchangeable and consolidat ion should not be referred to in earthworks specifications. . ) 1 2 1 3 5 0 0 1 (
1.2.6 Dispersive soil
Soil that has the ability to pass rapidly into suspension in the presence of water. 1.2.7 Foundation
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The earth material immediately underlying and supporting any engineering structure; thus, the foundation for a fill is the stripped surface and a fill itself can be a foundation for a building. 1.2.8 Lot
A lot is an area of work that is essentially homogeneous in relation to material type and moisture condition, rolling response and compaction technique, and which has been used for the assessment of the relative compaction of an area of work. 1.2.9 Pavement material
Material that is used in the construction of pavements. NOTE : Pa vement mat erial is gen eral ly gra nular and oft en man ufa ctured from hard rock sources (e.g., crushed rock).
1.2.10 Reactive soil
Clay soil, for which a change in moisture content results in a sufficient change in volume to affect the engineering performance of any structure in contact with it. 1.2.11 Relative compaction
1
For cohesive soils, the dry density ratio determined in accordance with AS 1289.5.4.1, or the Hilf density ratio determined in accordance with AS 1289.5.7.1.
2
For cohesionless AS 1289.5.6.1.
soils,
the
density
index
determined
in
accordance
with
1.2.12 Rockfill
Fill composed almost exclusively of fragments of broken rock. It generally consists of a large portion of gravel and larger sized fragments, and ma y contain large open voids. 1.2.13 Structural fill
Any fill that will be (or may be), required to support structures or associated pavements, or for which engineering properties are to be controlled. Sometimes referred to as controlled or engineered fill. 1.2.14 Subgrade
The earth material on which it is proposed to construct a pavement. This is often taken as being to a depth of 300 mm below the level from which the formal pavement is constructed.
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1.2.15 Topsoil
A surficial soil containing some organic matter, usually darker than the underlying soils. 1.3 DESIGNATION OF PERSONNEL
For the purpose of this Standard, the following terms are relevant:
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(a)
The owner —someti mes referred to as the proprietor or t he principal .
(b)
The designer.
(c)
The geotechnical professional —a person suitably qualified and experienced in geotechnical principles as applied to earthworks.
(d)
The superintendent —the principal’s authorized pers on, sometimes referred to as the engineer or the architect.
(e)
The constructor —som etimes referred to as the contractor or the builder.
(f)
The geotechnical inspection and testing authority (GITA)—an organization that should be used for the inspection and testing as detailed in Section 7 and Section 8.
(g)
The geotechnical testing authority (GTA)—an organization that should be used for the testing as detailed in Section 7 and Section 8.
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S E C T I O N
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I N V E S T I G A T I O N , A N D D E S I G N
P L A N N I N G
The investigation, planning and design for projects involving earthworks require the designer give consideration to those factors that may affect the works . Before site works are commenced, some or all of the following details may need to be taken into account: (a)
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Approvals The precise terms of approval of the project by relevant authorities, including local government and heritage, planning and environmental protection agencies, can influence the execution of the works. The necessity to obtain approvals will extend to off-site locations, such as borrow areas and haul routes.
(b)
Services Inspections, in conjunction with the relevant authority where necessary, to locate existing and proposed public utility services, which may be affected by or affect the works. Written requirements, in respect of such services, should be obtained from each relevant authority.
(c)
Adjoining property Examination to assess whether there is a potential for damage due to vibration, excavation, filling, noise, run-off, dust or other effects of the earthworks, and liaison with the adjoining owners.
(d)
Regulations Working hours on site, warning signs, fencing or security requirements and emanations from the site including dust, water, silt, noise or smoke, are controlled by regulations. These regulations are in addition to the civil rights of adjoining owners and the public.
(e)
Preservation items Surveys necessary to identify and locate aboriginal or historic relics, heritage items or rare flora or fauna, which may require preservation or relocation.
(f)
Reha bilitation Rehabilitation of areas affected by construction activities such as borrow pits, stockpiles, excavated or fill batters, spoil disposal areas, haul routes, stormwater control, camp, office and workshop sites, should be included in the drawings and specifications so that materials such as topsoil, mulched native vegetation (which can contain useful seedstock and nutrients) and bulk fill materials used for rehabilitation are identified and preserved for re-use. Rehabilitation works should be completed before the constructor vacates the site.
(g)
Drainage Temporary or permanent diversion of permanent or ephemeral watercourses prior to or during construction of the earthworks and associated works may affect the quantity or quality, or both, of the stormwater run-off. Therefore, special provisions may be necessary to minimize the effects and to protect the legal rights of adjacent and downstream landowners. Failure in providing for such provisions could lead to litigation and delay in completion of the earthworks project.
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Approval from the relevant authorities should be obtained prior to either the placement of fill on flood-prone lands or construction of drainage structures, i.e., culverts in natural w atercourses. The placement of fill or construction of cuts may impact the flow of subsurface water and may lead to localized instability. Special provisions may be necessary to account for the potential effect of the work s in this situation. (h)
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Erosion and siltation Protection of the earthworks from erosion, both during construction and after construction, needs to be taken into account. Run-off from the works, and areas affected by the works, may be subject to special provisions (see Item (g) above).
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(i)
(j)
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Sloping ground Special precautions where the earthworks are constructed on sloping ground include— (i)
benching of the surface of the natural ground to assist in the placing of the fill and to key the fill to the foundation soil;
(ii)
berms or benches above, within, or at the foot of cuts to intercept stormwater run-off or detritus; and
(iii)
special works.
Slope stability The basis for the assessment of the short- and long-term stabilities of natural slopes, cut-face slopes and fill slopes is— (i)
local experience with similar materials under similar conditions; or
(ii)
geotechnical investigation and analysis.
Each stability assessment needs to take into account any existing slopes, proposed undercut and surcharge of the slopes and the effect of water seepage on the slopes. Each slope should be selected with regard to the required access, including maintenance, e.g., mowing. (k)
(l)
Zoning Zones for fill may be designated by specific locations and levels within the earthworks. The bases for the selection of fill within zones are— (i)
easily compacted fill near existing structures, to minimize the comp active effort and consequent risk of damage;
(ii)
granular fill in areas that may become wet during compaction;
(iii)
fill containing large fragments, i.e., rock or building rubble, not within the top 600 mm or at greater depth if trenches are to be constructed for footings or services, or piers or piles have to penetrate the fill; and
(iv)
saline fill not within the top 600 mm where vegetation may be established.
Soft or compressible foundation soils Soft or compressible soils do not form a good foundation on which to place and compact fills, and may need to be excavated. Alternatively, fill (which is readily compactable) may be placed in the lower levels of the earthworks immediately above such soils. Geosynthetics or some other ground improvement techniques may also be considered (see Item (v)). To minimize displacement of such soils during construction, the earthworks should be programmed to avoid unnecessary loading of the foundation, e.g., appropriate routing of fill haulage equipment or stage construction. The calculation of quantities needs to take into account the effect of compression of the foundation soils.
(m) Reactive soils The moisture content of reactive soils after compaction of fills should approximate the estimated long-term moisture content, which may be about the same as the moisture content for the undisturbed reactive soils at or about the depth of seasonal influence. (n)
Low density or potentially collapsing soils Low density or potentially collapsing soils lose volume when compacted in or beneath the earthworks. Calculation of quantities needs to take into account the effect of compression of the fill or foundation, or both.
(o)
Existing filled grou nd Existing filled ground, for which the conditions of the placement are not adequately documented as described in Clause 3.4, should not be assumed to be either of the standard of compaction or of the composition adequate to support fill or any other loads.
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Site investigations, which may include test pits, test bores, test rolling (see Clause 5.5), or other methods, are necessary to assess the degree of compaction and composition of the existing filled ground. Analysis of the results obtained from these investigations will allow an assessment of the adequacy of the existing filled ground or the extent of remedial works that may be required. Such remedial works could include complete removal. (p)
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Non-potable water The suitability of non-potable water for increasing the moisture content of fill should be evaluated by field and laboratory trials. Saline waters should not be used— (i)
in the upper layers of fill, beneath either bituminous sealed pavements or areas where vegetation may be established; and
(ii)
in fill where steel is buried.
(q)
Trenches Excavations for trenches require special consideration for support. Relevant authorities place limitations on the maximum depth to which trenches may be excavated without shoring.
(r)
Compaction moisture content The optimum moisture content determined by laboratory methods is only a guide for field construction, as the optimum moisture content for compaction under field conditions will depend on the material type, equipment used, the layer thickness and the nature of the foundation. In general, the heavier the compaction effort or the thinner the layer, the lower the optimum moisture content. Increased compaction effort may cause the soil to approach saturation and higher densities may not result.
(s)
Surcharging of slopes Cut face and fill slopes, sides of trenches and slopes supported by retaining walls should not be loaded, e.g., by construction equipment, materials, soil and the like, unless the assessment of the slope stability (see Item (j)) included an allowance for particular load(s).
(t)
Calculation of quantities In calculating quantities of fill, the following should be taken into account: (i)
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Volume changes due to excavation, spreading and compaction. NOTE : The degree of volu me change is depe nden t on the typ e a nd geol ogical origin of the material and required relative compaction. It can be assessed as part of the site investigation, using field density tests and laboratory compaction tests.
(ii) (u)
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Compression of the foundation (see Items (l) and (n)).
Physical separation of dissimilar materials Filters, comprising material of selected particle size distribution and geosynthetics (see Item (v)), may be used to avoid the mixing of materials after placement. Filters and geosynthetics are used to avoid— (i)
soft materials being forced into voids of granular material; or
(ii)
erosion of fine material into adjacent granular material.
(v)
Geosynthetics Proprietary products are available with particular properties suitable to act as a filter, drainage layer and/or physical separator to allow water flow whilst avoiding migration of soil particles or as a tensile reinforcement layer. Such materials may be construction expedients, or may form part of the permanent earthworks. Geosynthetics should be carefully chosen for the intended purpose and have an adequate service life under the intended conditions.
(w)
Vibration Construction activities, particularly those using equipment such as compactors or blasting, may cause vibrations that could damage nearby structures, either directly (due to the vibration transmitted to the structure) or indirectly (for example, by causing settlement of the foundations).
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(x)
Contamination Any known or suspected ground or groundwater contamination should be investigated. Relevant authorities have set limits on the quantity of contaminants permitted in ground, in various applications. Removal of contaminated soil from the site is likely to require special consideration, such as classification. Similarly, allowing contaminated soil to be imported or to remain on site may require approval from the relevant authority. The impact of any investigation on planned earthworks, including safety and environ mental aspects, should be considered.
(y)
Retaining walls The compaction of fill against retaining walls may induce higher pressures than adopted in the design. The nature of the fill to be used, the specified level of compaction, and the type of compaction equipment to be used, should be assessed in selecting design fill loads on retaining walls.
(z)
Potential acid sulfate soils In certain areas, particularly in coastal marine deposit areas, the presence of considerable amounts of iron sulfates is possible. Disturbing or exposing these soils to air may cause the formation of sulfuric acid. Excavation and movement of such soils are subject to strict environmental controls that normally expect chemical treatment to avoid contamination of streams and drains. Consultation with the relevant environmental authority is required prior to the excavation or use of such soils. NOTE : For sampli ng and inv est igation of soil for iron sul fate content , s ee AS 4482. 1.
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S E C T I O N
3
D O C U M E N T A T I O N
3.1 GENERAL
This Section includes details of the documentation for the design and construction of an earthworks project. 3.2 INVESTIGATIO N AND PLANNING
Investigations for the planning of earthworks for use by the designer, the constructor and other interested parties should include the following: . ) 1 2 1 3 5 0 0 1 (
(a)
Outline of the need for, and objectives of, the project.
(b)
Site investigation of the project and any associated sites, covering, where applicable, the— (i)
d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
condition of the site(s) including— (A)
present uses, i.e., buildings and v egetation; and
(B)
evidence of past uses, i.e., demolition, filling and vegetation;
(ii)
foundation and subgrade materials;
(iii)
special areas due to groundwater, seepage, rock, r eactive and collapsing soils;
(iv)
available fill materials and, where applicable, details of the overburden;
(v)
suitability of the fill materials for the intended purposes;
(vi)
classification of materials to be removed off site;
(vii) availability of suitable pavement materials; (viii) quantity and quality of the available water; and (ix)
suitability of water for the placement of the fill.
(c)
Where applicable, an outline of other plans that have been considered in the investigation. This should include the points discussed in Section 2.
(d)
The quality assurance requirements for the project.
3.3 DESIGN AND SPECIFICATION
The functional requirements of the design should be documented in the specification and drawings for the earthworks project. This documentation should be sufficiently complete to allow the constructor to unambiguously carry out the works, and for t he superintendent (and the geotechnical inspection and testing authority, as necessary) to be able to interpret the design and administer the contract. Such documentation will typically include (or have consciously excluded), the following, as well as any other matters that may be of particular importance to the particular project: (a)
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Adequate specification and drawings to allow the proper pricing, planning, execution and supervision of the works. Plans, sections and elevations should clearly show areas of earthworks, identifying areas requiring specific treatments. Particularly on larger projects, the specification and drawings should adequately define the following: (i)
The areas in which spoil may be dumped or stockpiled.
(ii)
Restrictions on clearing and stripping.
(iii)
Drainage requirements during and after construction.
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(iv)
Criteria for selection of materials for placement in various parts of the fill and for material to be excluded from fill. Material descriptions should be clear, unambiguous and in accordance with AS 1726.
(v)
Criteria for standard of surface trim of completed earthworks.
(vi)
Details of tests, including minimum frequency, to be carried out for testing to ensure the fill complies with the specified criteria.
(vii) The scope of the commission to be given to the geotechnical inspection and testing authority (see Clause 1.3).
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(viii) Either the methods to be used for construction or the requirements to be met by test in the finished project. It is generally unwise to mix performance and method specifications. Where a performance specification is adopted, restrictions on methods should be limited to those absolutely necessary (for example, to limit the risk of damage to nearby structures). (b)
Site investigation information, including that given in Clause 3.2(b), together with details of, and provision for, access to any further relevant information for the purpose of design or construction planning. Selective provision of available site investigation data can give rise to serious problems, either engineering or legal, or both, and should not be done without due consideration of the issues involved. An overview of the issues is given in a m onograph on this subject. *
(c)
Any other relevant information in the possession of the designer.
3.4
CONSTRUCTION
Adequate records need to be kept during construction, including conditions encountered, works as executed, testing and any alterations to the specification and drawings. As a minimum, these records should show the following: (a)
The areas in which fill is placed.
(b)
Levels after stripping.
(c)
Location of any trees or large shrubs that may have been removed.
(d)
Materials exposed after stripping and the criteria upon which the decision to cease stripping was made.
(e)
Levels after completion of the filling.
(f)
Details of test rolling, if un dertaken.
(g)
Types of fill material in various zones.
(h)
Sources of fill material in various zones, where applicable.
(i)
Location and level of each compliance test, together with test results. Where a test is a retest of a lot that was previously rejected, this should be stated.
(j)
Action taken where testing indicated that the specified criteria had not been met.
Any areas in which the fill material or compaction is to be of a lesser standard or a greater standard than elsewhere on the site should be clearly identified.
*Guidelines for the provision of geotechnical information in construction contracts , Canberra, The Institution of Engineers, Australia, 1987 ww w.s tan dard s.o rg. au
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3.5 SITE RECORDS
Daily diaries and detailed drawings of works, as executed, should be maintained by site staff. Typical site records are— (a)
a daily geotechnical report, generally appropriate for larger projects;
(b)
a geotechnical site visit record; and
(c)
an earthworks summary report, generally appropriate for small projects.
NOTE : Typic al exa mples are given in App endi x B and cont ain onl y rel evant tech nic al information relating to the work as executed. It is likely that records of other aspects of the works, such as weather conditions, work hours, breakdown and standby times, instructions issued, conversations between parties, visitors to the site and the like may need to be kept by the superintendent, the constructor or other parties, for the purpose of contract administration. . ) 1 2 1 3 5 0 0 1 (
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M A T E R I A L S
4.1 GENERAL
The earthworks for most projects for which this Standard is intended will involve cut-to-fill operations using on-site materials. Importation of suitable material on to the site may also be required. In some instances, materials may be encountered which are unsuitable for use as fill, or which may r equire particular attention in their placement and control, if they are to b e used. This Section provides guidelines regarding material acceptance and control. It is important to note that the primary requirement of a fill is dimensional stability, that is, a fill should not settle nor heave excessively in service. This relies upon control of (among other things) the shrink-swell properties of the near surface materials and the modulus or stiffness of the material. It is neither usual nor convenient for these properties to be directly controlled in works and as such the usual forms of specification only indirectly consider these properties.
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4.2 MATERIALS SOURCED ON SITE
On many projects it may be assessed that material, or portion of the material, to be won from cuts or borrow pits on site will be suitable for the works. In such cases, the specifier may have an adequate understanding of this material to be able to relax the requirements that might apply to imported or other material. 4.3 UNSUITABLE MATERIALS
Some materials are unsuitable for forming structural fill and should be either removed to spoil or used in non-critical areas. Unsuitable materials may include— (a)
organic soils, such as m any topsoils, severely root-affected subsoils and peat;
(b)
materials contaminated through past site usage which may contain toxic substances or soluble compounds harmful to water supply or agriculture; NOTE : D ispo sal of suc h mat erials wil l genera lly req uire special cons iderati on, and often wil l be subject to control by regulatory authorities.
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(c)
materials containing substances that can be dissolved or leached out in the presence of moisture (e.g., gypsum), or which undergo volume change or loss of strength when disturbed and exposed to moisture (e.g., some shales and sandstones), unless these matters are specifically addressed in the design;
(d)
silts, or materials that have the deleterious engineering properties of silt;
(e)
other materials with properties that are unsuitable for the forming of structural fill; and
(f)
fill that contains wood, metal, plastic, boulders or other deleterious material, in sufficient proportions to affect the required performance of the fill.
In some circumstances a design may allow for the use of some of these materials in structural fill. Before allowing for such use, advice from a g eotechnical professional should be sought.
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4.4 SUITABLE MATERIALS
Most naturally occurring soils, with the exceptions specified in Clause 4.3, are capable of being compacted to form a structural fill. Similarly, weathered rock that can be ripped and broken down by co mpaction will be generally suitable for use as structural fill. The applicability of some materials will depend, among other things, on their in situ condition at the time of the work, the intended end use of the fill, and on the economics of winning, and placement to, the specification requirements. Special consideration may be required for the f ollowing:
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(a)
Clays of high plasticity, which may be reactive and need to be selectively placed within the fill and under strict moisture and density control.
(b)
Material, which, after compaction, contains large particles, which may lead to difficulties in the excavation of trenches for footings or services, driving of piles or drilling of piers (if this is necessary).
(c)
Overwet materials (as may b e encountered in low-lying areas), which may be difficult to satisfactorily dry out within an economical time for use in the project.
(d)
Single-sized or gap-graded gravels or rock fill that will not break down on compaction, leaving voids into which finer material may subsequently migrate.
(e)
Saline, chemically aggressive or polluted soils, and carbonate soils where acid disposal may occur.
(f)
Potential acid sulfate soils.
(g)
Materials that cannot be tested to demonstrate compliance with the specification.
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C R I T E R I A
5.1 GENERAL
In most situations, the required compaction should be specified as a minimum relative compaction and not as an absolute dry density. The means by which such minimum relative compaction will be specified will vary for each earthworks project. Projects involving large areas of fill may use ‘statistical’ acceptance criteria (see Note), but otherwise it will be common to adopt a ‘no value to be less than’ acceptance criterion. It should be appreciated that the minimum value of relative compaction specified may be different for each type of acceptance criterion for the same expected overall level of compaction. . ) 1 2 1 3 5 0 0 1 (
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NOTE : The use of averaging or so- called ‘st ati sti cal ’ acce pta nce criteria for eart hworks is common practice for large projects and is likely to further increase as this method of quality acceptance testing becomes familiar; however, control-testing schemes involving statistical acceptance criteria will be generally outside the scope of the projects to which this Standard applies. Some notes on the basis of such schemes are given in Appendix C. If, in the view of the project personnel, statistical criteria should be applied, specific advice should be obtained from a geotechnical professional.
5.2 COMPACTION OF SOILS
This Section is applicable to soils that contain less than 20% by mass of particles coarser than 37.5 mm after field compaction. This will include many of the m aterials used in earthworks projects to which this Standard is applicable. Soils containing more than 20% of particles coarser than 37.5 mm cannot be tested for relative compaction usin g the procedures of AS 1289. Clause 5.4 discusses this situation. Minimum relative compaction values for different applications of various projects are given in Table 5.1. The values are based on historical data, which have taken into account the uncertainty of measurement for each of the tests involved. They have been found to deliver acceptable performance, and are for a specification of the ‘no value to be less than’ type. They are not applicable where statistical control criteria (see Note to Clause 5.1) are applied. In the latter circumstances, the minimum acceptance criteria will be different, and dependent upon the scheme adopted. This Standard does not give guidance on such values. Guidelines for minimum r elative compaction values are given below. These should be taken as minimum values in areas of structural fill. It is possible that more stringent criteria may be applicable in some circumstances, e.g., to assist in settlement control, shrink-swell behaviour or to provide increased strength. Similarly, in non-structural fill areas, the designer may wish to provide f or less stringent requirements.
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TABLE 5.1 MINIMUM RELATIVE COMPACTION Minimum relative compaction, % Minimum density ratio (at standard compactive effort) (Cohesive soils) (see Note 1)
Minimum density index (Cohesionless soils) (see Note 2)
95 (see Note 3)
70
98 (see Note 4)
75
(a) General fill
95
70
(b) Subgrade (to a depth of 0.3 m)
98
75
Item
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1
Residential—lot, fill, house, sites
2
Commercial—f ills to support minor loadings, including floor loadings of up to 20 kPa and isolated pad or strip footings to 100 kPa
3
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Application
Fill to support pavements (see Note 5)
NOTES : 1
Density ratio may be either dry density ratio (see AS 1289.5.4.1) or Hilf density ratio (see AS 1289.5.7.1) as applicable. These test methods require reporting to the nearest 0.5% and this is assumed in these values.
2
Density index as a means for control of achieved relative compaction may be difficult to use and interpret. Local correlations with other methods may exist and can be used where these are well established.
3
Development on this fill will be restricted to single- and some double-storey houses, with floor slab average imposed bearing pressure not exceeding 20 kPa, and strip or pad footings not exceeding imposed bearing pressures of 100 kPa. Residential developments imposing higher pressures other than these are considered as commercial. A minimum dry density ratio of 98% or higher may need to be considered if collapse on saturation or excessive settlement is likely to occur.
4
Commercial developments are likely to impose loads on fills that will have a more severe effect than those of houses, even where contact pressures are limited to those stated. The designer, in association with a geotechnical professional, should assess the load-carrying capacity and expected deformations associated with proposed filling and be satisfied the fill can perform its required function. Where highly loaded fills are proposed, the minimum relative compaction may need to be increased.
5
Where pavements will be required to carry a significant volume of heavy vehicles, the minimum compaction criteria for the upper levels of the fill may need to be reviewed. For all pavements, it is essential that the specification for compaction of subgrade materials reflects the condition under which tests carried out for pavement thickness design are conducted.
6
Local practice in some areas for well-known materials may rely on acceptance criteria based on other parameters, e.g., penetrometers as described in AS 1289.6.3.2 and AS 1289.6.3.3.
7
The ground surface exposed after stripping should also be compacted in accordance with Table 5.1, to a depth of not less than 150 mm. If this is not carried out or not possible (for example, due to pre sence of soft ground), the consequences should be taken into account by the designer.
8
The above criteria should be applied in conjunction with visual appraisal of the standard of compaction by the superintendent or as otherwise provided in the contract. The specification should define the circumstances where visual appraisal (including test rolling, if appropriate) may override test results for relative compaction, as per Section 7.1.
9
It is recognized that in some parts of Australia, such as Central Australia and much of Western Australia, the use of modified compactive effort is preferred, because the natural moisture content more closely approximates the modified optimum rather than the standard optimum. This Standard does not give guidance on minimum relative compaction requirements in these areas.
Advice from a geotechnical professional should be taken in relation to relative compaction and placement moisture contents. The designer should be conscious of not over-specifying the level of compaction required, simply for the sake of expediency. In some soils, e.g., reactive clay soils, over-compaction may actually impair subsequent performance. Furthermore, increasing the required relative compaction may result in substantial cost increases and possible delays in completion. ©
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In clay soils, large modern compaction equipment will often operate more effectively at moisture contents that are substantially lower than the optimum moisture content determined in the standard compaction test (see AS 1289.5.1.1); however, many types of clays placed in this manner may swell significantly and lose strength if they are wetted up after compaction. Such compaction of fill may affect the site classification determined in accordance with AS 2870, or result in subgrade strengths less than assumed in design. Some materials degrade rapidly during compaction (e.g., some weak or weathered rocks); therefore, care is required to avoid over-compaction of such materials. In such a situation, the designer may need to consider revision of the relative compaction guidelines of Table 5.1 to take account of the associated changing compaction characteristics. This will be particularly important where further breakdown occurs during laboratory compaction. . ) 1 2 1 3 5 0 0 1 (
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NOTE : If further brea kdow n occu rs duri ng laboratory compaction, the res ulting moi stu re densit y relationship may not satisfactorily relate to that which existed at the time of field compaction. As a consequence, comparison of the field dry density to the laboratory maximum dry density (MDD) may not adequately reflect the design intent (if MDD reduces with breakdown), or may unfairly penalize the constructor (if MDD increases with breakdown). Where such variations are likely, testing should be carried out at the time of design and realistic requirements, which reflect the design intentions, should then be specified. It is not appropriate in these circumstances to sample material for laboratory testing before field compaction (see Clause 7.4).
5.3 PLACEMENT MOISTURE CONTENT
For potentially reactive or moisture-sensitive soils it will be necessary to specify a range of moisture content within which the fill is to be placed and compacted, as their subsequent engineering performance may be dependent upon their placement moisture. It is not necessary to routinely specify and enforce moisture control in other non-critical areas, or in materials where subsequent engineering performance is unlikely to be adversely affected by placement moisture. Inclusion of such a requirement is likely to increase the cost of placement. Where it is required to reduce the potential for swelling of reactive clays when placed as compacted fill, it may be desirable to specify a maximum as well as a minimum level of relative compaction, and to be quite specific about the moisture content at which the compacted fill is to be placed and maintained, until topsoiling or similar takes place. It is desirable for reactive clays to be placed close to their equilibrium moisture content (not a soil property, but dependent on the soil and environment). In temperate climates, the equilibrium moisture content is often close to the optimum moisture content (standard compaction). In arid and semi-arid environments, the equilibrium moisture content may be considerably drier than in temperate climates. Material in borrow areas at or about the d epth of seasonal influence is often close to the equilibrium moisture content and, therefore, the potential for problems may be minimized by placing material directly from cut to fill. Where reactive soils are to be used as fill, it will normally be necessary to specify the placement moisture content to be within a specified range, e.g., ‘90% to 110% of the standard optimum moisture content (see A S 1289.5.1.1), or ‘moisture variation to not exceed ± 2%’. 5.4 COARSE MATERIAL
Where ripped rock or coarse material is used for filling, the after-compaction quantity of material coarser than 37.5 mm may exceed 20%. With such material, the test procedures for in situ determination of dry density ratio specified in the relevant parts of AS 1289 are not applicable and special consideration should be given to alternative methods of testing for compaction. In such circumstances, it is comm on to adopt a method specification.
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A method specification will usually include required moisture conditioning, a minimum number of passes of a given roller and a maximum layer thickness. Such method specification should be decided upon once the nature of the material to be placed is known and after consideration of the proposed use of the fill. The method specification should be part of the documentation (see Clause 3.3), although it may need to be developed in conjunction with a geotechnical professional. The method specification for placement of coarse granular material may include test rolling, to assist in evaluating the stability of fill materials being placed (see Clause 5.5). 5.5 TEST ROLLING
Areas upon which structural fills are to be constructed, all layers of structural fill, and materials within 150 mm of permanent subgrade level in cuttings should be co mpacted so as to be capable of withstanding test rolling without visible deformation or springing.
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Suitable plant for test rolling procedures may consist of the following:
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(a)
Static smooth steel wheeled rollers with a mass of not l ess than 12 t and a load intensity under either the front or rear wheels of not less than 6 t/m width of wheel.
(b)
Pneumatic tyred plant with a mass of not less than 20 t and a ground contact pressure under either the front or rear wheels of not less than 450 kPa per tyre. The area over which this ground contact pressure is applied should be not less than 0.035 m 2 per tyre.
(c)
Highway truck with rear axle or axles loaded to not less than 8 t each with tyres inflated to 550 kPa.
Fill layers should be test-rolled immediately following completion of compaction. If further test-rolling is required at some later date, the surface should be moisture-conditioned, as required, and given not less than four coverages of the testing roller before test rolling resumes. Any areas where visible deformation or springing is detected by test-rolling should be rectified and represented for test-rolling, or the opinion of the designer should be sought. Where unstable areas exceed 20% of the area being considered by test-rolling, the whole of the area should be ripped, recompacted and re-p resented for test rolling. An alternative method for test-rolling is to use an impact roller or impact compaction, a non-circular towed or self-propelled module that imparts a high energy dynamic force. Impact rollers can be utilized to identify weak zones or soft spots, but will tend to loosen the surface layer. 5.6 OTHER MATERIALS
Unprocessed waste materials such as demolition rubble are extremely variable and should only be accepted as structural fill after due consideration by the designer, preferably in conjunction with field trials. The specification for the supply, placement and co mpaction of such fill should then be clearly stated. Impact rollers are often suited to test rolling such fills, although the testing regime requires site-specific attention. 5.7 TRENCHES
Trenching infill for service installation, or like works, is common in commercial and residential developments. It is important that, in such areas, rapid lateral changes in the engineering properties of the ground do not occur. Compaction of backfill is important and should be clearly specified, in terms of relative compaction, and controlled. The compaction of the backfill should be compatible with that specified by the designer and the minimum requirements of the relevant statutory authority. The practice of flooding sands may be insufficient to achieve compaction of backfill and additional compaction methods may be required. ©
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C O N S T R U C T I O N
6.1 SITE PREPARATION 6.1.1 General
This Section covers specific activities that are likely to form part of any earthworks project and are presented in the approximate order of works. Government environmental regulations may apply to some aspects covered herein and, where conflict between these exists, such regulations will take precedence over these guidelines. 6.1.2 Fencing
Fencing should be installed as required, before earthworks commence, to define the limits of the work , to restrict construction plant to the site or for public protection.
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6.1.3 Drainage, erosion and sedimentation control
Earthworks should avoid the siltation or erosion of adjoining lands, streams or watercourses. Drainage, erosion and sedimentation control should be installed before the natural surface is disturbed. Sedimentation basins, stream diversion or other works may be appropriate in some environments or topography. Careful planning is required for these works. Erosion and sedimentation control may be aided by minimizing the area of disturbance and by the progressive re-vegetation or development of t he site. 6.1.4 Site clearing
The site should be cleared (to the minimum extent required for the work) of all trees, stumps and other materials unsuitable for incorporation in the works. The roots of all trees and debris, such as old foundations, buried pipelines (and the like) should be removed to sufficient depth to prevent inconveniences during subsequent excavation or foundation works. Resulting excavations should be backfilled and compacted to the same standard as t hat required for subsequent filling operations. Disposal of cleared combustible material may have to be off-site if clean air or bushfire regulations prevent on-site burning (see Clause 6.1.8). 6.1.5 Stripping
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The area on which the fill is to be placed and the area from which the cut is to be removed should be stripped of all vegetation and of such soils as may be unsuitable to support the proposed loadings or for incorporation in fills subject to density, moisture or other specified controls. Topsoil and severely root-affected soils may need to be stripped as unsuitable material or as required for subsequent revegetation. Geotechnical assessment of the depth and quality of topsoil or vegetal cover of the underlying soils and of the quality and depth of the proposed fill may obviate the need for such stripping in some circumstances. All stripped materials should be deposited in temporary stockpiles or permanent dumps in locations available for subsequent re-use if required, and where there is no possibility of the material being unintentionally covered by, or incorporated in, the earthworks.
A1
Special care is needed to ensure that materials that will inhibit or prevent the satisfactory placement of subsequent fill layers are not allowed to remain in the foundations of fills.
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Consideration should be given to the in-service drainage characteristic of the fill to be placed, particularly to the likelihood of instability caused by moisture build-up over impervious foundation layers or their inability to form a continuous or homog eneous mass. 6.1.6 Slope preparation
Where a fill abuts sloping ground, benches should be cut in the ground. It is unlikely that slopes flatter than an 8:1 (horizontal to vertical) gradient will require benching. The benches should be shaped to provide free drainage. The depth of bench should be not less than 100 mm, but generally be of the order of 300 mm; however, it may vary depending on the natural slope of the ground, the nature and proposed end-use of the fill and the equipment being used. The boundary of cut-and-fill areas requires special consideration. All topsoil and other compressible materials should be stripped prior to benching into the natural material of the cut zone.
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Wherever practicable, the ground surface exposed after stripping should be shaped to assist drainage and be compacted to the same requirements as for the overlying layers of fill, utilizing suitable equipment, in accordance with Note 7 to Table 5.1. Subject to the required end-use of a site, the surface exposed upon completion of excavation works may also require preparation prior to fill placement proceeding. This will typically be the case whenever subsequent fill is to be placed, as might be the case for pavement construction or base material beneath a floor slab, or in the case of existing fill that is to be retained in situ or for the identification of potential weakness in the subgrade. In such circumstances, it will be necessary to treat the area in an appropriate manner. Such treatment may include loosening the exposed excavation surface by scarifying to a depth of at least 150 mm, and to then moisture-condition and compact this loosened material. The depth to which scarifying carried out should not exceed that which can be compacted. Alternatively, existing fill or weak or variable subgrade materials may respond to ground improvement using an impact roller or impact compaction and, if considered appropriate, a trial or specification should be applied. In ground where it is impracticable to achieve compaction of the existing or stripped surface, design advice should be sought from a geotechnical professional. In such cases, a working platform generally of granular material, end-dumped and spread in sufficient depth to allow the passage of earthmoving equipment with minimal surface deflection, may provide a suitable foundation for subsequent filling. In some cases, it may be appropriate to place geosynthetics across the natural or stripped surface before such fill placement is carried out. Localized springs or seepages in the foundation area, detected during site investigation for the work, should be noted and allowed for in the design. If such problems are not detected until the works are in progress, they should be investigated so that measures such as subsoil or rock rubble drains may be designed for incorporation in the works. 6.1.8 Off-site disposal
All materials arising from site preparation works should be managed in accordance with the requirements of the relevant regulatory authorities. This may require segregation by material type, classification and, where required, disposal at facilities appropriately licensed to receive the particular materials.
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6.2 FILL CONSTRUCTIO N 6.2.1 General
Planning for fill construction should include, but not be limited to—
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(a)
the quantity and quality of t he fill material;
(b)
the expected rate of output of the earthmoving, delivery and spreading equipment;
(c)
the compaction specification to be met; and
(d)
the availability and effectiveness of particular items or types of compaction equipment.
The number of passes of a particular roller required to compact a layer of specified thickness at a given moisture content (or within a specified moisture range) can only be established in the field. NOTE : Guida nce on the suitabi lit y of compaction equi pment for vari ous typ es of fil l mat erial is given in Appendix D.
6.2.2 Placing fill
The quality of fill material and the control tests to be used as the acceptance criteria should be specified in the documentation (see Clause 3.3). Fill material should be placed in near-horizontal layers of uniform thickness, deposited systematically across the fill area. The thickness of each layer should be appropriate to the equipment to be used and test procedures to be adopted. This will vary according to the material being placed and the equipment being used. For example, in open areas and with large rollers it may be p ossible to satisfactorily compact fill in layers of up to 400 mm loose thickness. In confined areas layers as thin as 100 mm may be required. With careful consideration, adequate compaction may be achieved on thicker layers with some equipment. It may be necessary to excavate or ‘box’ into the existing surface at the edge of fills to provide a suitable junction with the existing surface to avoid feathered edges. The method of excavation, transport and depositing of fill material should ensure that the fill is placed in a mixture as unifor m as practicable. Such uniformity will assist in providing consistent relative compaction from the chosen plant and work practices, and in avoiding material variations, which may affect the long-term performance of the fill. Each fill layer thickness should be such that the bottom of each layer is compacted to the specified relative compaction and can be tested by the specified test methods. Whilst compaction may be achieved in deeper layers by using heavier equipment or increasing the number of passes, the relative economy of various options may need to be examined, if a particular layer thickness is not specified. Before any loose layer of fill is compacted, the material and its moisture condition should be as uniform as practicable throughout its depth. The maximum particle size of any rocks or other lumps within the layer, after compaction, generally should not exceed two-thirds of the compacted layer thickness. If there is a delay in the placement of subsequent fill layers, previously accepted layers should conform with the specification before further fill is placed. If these layers have wetted up or dried out, they may inhibit compaction or cause heaving of subsequent layers. In some instances, drying of the fill may be deleterious, especially with reactive soils. The standard of surface trim of the completed earthworks should be specified in the documentation (see Clause 3.3).
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6.2.3 Fill moisture control
If limits on the moisture condition of fill material during compaction are specified, they should be such that they still allow the required degree of compaction to be achieved with reasonable effort. If the moisture content of the fill falls below the specified minimum, water should be added either on the fill or in the cut/borrow area before it is transported to the fill area. Water applied on the fill should be finely sprayed and uniformly blended throughout the full depth of uncompacted material. If the moisture content of the uncompacted fill is non-uniform, the material should be mixed to provide a consistent moisture distribution. Care is needed to ensure that mixing or blending does not produce segregation of the fill material. If the moisture content of material is above the specified maximum, drying of the material may be accelerated by aeration or by blending with drier materials. If the moisture content is such that it approaches saturation at the specified density, it may be difficult, if not impossible, to achieve the specified compaction.
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Control of moisture content should be applied not only to the upper layer of uncompacted material, but also to the material of the previously compacted layer. This surface material should be brought to within the specified moisture range before it is covered by a new layer.
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If rain is threatening or the site is to be left unattended, the upper surfaces of fills should be crowned and, if possible, sealed with rubber-tyred or smooth-wheeled plant and graded to prevent ponding. 6.2.4 Fill compaction
Each layer of fill should be compacted as a systematic construction operation, using plant that is specifically assigned to the compaction task and which tracks progressively across the surface of the fill. Construction and earthmoving plant may be routed to assist in this regard. Selection of the compaction equipment requires careful consideration of the job specification requirements. The plant should be capable of compacting all of the fill area, including its edges and junctions with the n atural ground. Fill batter faces should be compacted as a separate operation or, alternatively, overfilled and cut back. The trimmed and compacted batter face should have a roughened surface to reduce run-off velocities and aid revegetation, if required. Where testing of a lot shows that it does not comply with the specification it should be reworked and retested, as necessary, to confirm compliance. Additional moisture blending or drying out may be required to facilitate recompaction. The surfaces of all fill layers should be shaped to provide drainage and to prevent ponding, which will cause deterioration of previously compacted fill layers. 6.2.5 Surface heaving
Surface heaving results from the compaction of materials approaching saturation and inhibits further compaction. The development of surface heaving on fills m ay be avoided by the following:
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(a)
Ensuring that the moisture content of materials during placement avoids near saturation at the specified density.
(b)
Providing drainage on the surface of fills and preventing the ponding of water on fill layers.
(c)
Selecting appropriate earthmoving and compaction equipment.
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6.2.6 Fill adjacent to structures and in trenches
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Fill adjacent to structures such as pipes, culverts, abutments, retaining walls or other structural components, or the backfill of trenches, may need to take into account of some or all of the following: (a)
The strength or age of the structure(s), e.g., the quality of cast in situ concrete, before filling can commence.
(b)
The filter zone to be provided adjacent to weep holes or other subsoil drainage systems.
(c)
The quality of fill. Sand, natural gravel or quarry products may be specified to facilitate compaction in confined areas to minimize differential settlement, which might otherwise overload the structure or to divert seepage to subsoil or other foundation drainage systems.
(d)
The type and method of compaction compared with normal fill construction. Fill should be brought up equally on each side of pipes and culverts, to avoid unbalanced loading. The first layers of fill over the top of structures will require careful placement. The design should specify the depth of fill to be placed over pipes or culverts, or special conditions that might apply to other structures. In some cases, internal propping may be required if normal compaction is to be used immediately above or adjacent to structures.
(e)
The excavation and filling of trenches, or testing of trench backfill, may require special precautions to protect the safety of personnel or equipment involved in the work, based on relevant regulations and site-specific risk assessments.
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S E C T I O N
7
M E T H O D S
O F
T E S T I N G
7.1 GENERAL
This Section describes the procedures to be followed when carrying out acceptance testing of field compaction. In considering this Section, it will be necessary to have established the requirements of the specification for the work to be tested and of the relevant test procedures. Acceptance testing, based on a comparison of the density achieved in the field with that of some reference density established in a laboratory, provides an indirect measurement of the performance of the compacted fill material. Consequently, it is essential that the documentation (see Clause 3.3) include a satisfactory basis for achieving the r equired performance. Measurement of relative compaction in general is not sufficient to assess compliance and should be used in conjunction with visual inspection of the compaction process and, where applicable, test rolling.
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Strength or other tests may provide a measurement of the performance of the compacted fill material. NOTE : Co mment on the application of s tat ist ica l m eth ods in eart hworks is giv en in Appe ndix C.
7.2 FIELD DENSITY
Methods for the determination of field dry density are as follows: (a)
Direct The methods are as specified in AS 1289.5.3.1, AS 1289.5.3.2, AS 1289.5.8.1 and AS 1289.5.5. NOTE :Al though the met hod spec ifi ed in AS 1289. 5.8.1 relies upon correlation of recorded density count against standard blocks (see AS 1289.5.8.4), provided calibration has been carried out as specified, it is for the purpose of this Standard, a direct method.
(b)
Indirect These methods provide an empirical measure of achieved density by measurement of another engineering property, principally shear strength. Correlation with local materials and conditions is required. The methods include those specified in AS 1289.6.3.2, AS 1289.6.3.3 and AS 1289.6.5.1. Correlation with local materials and conditions is required. Such correlation should include the effects of depth/confining pressure, moisture content, material type and local conditions when comparisons with the methods specified in Item (a) (this Clause) are proposed.
The specification should designate which test procedure governs acceptance. 7.3 ESTABLISHME NT OF A REFERENCE DENSITY FOR CALCULATION OF RELATIVE COMPACTION
To permit relative compaction to be calculated, it is necessary to establish a laboratory reference density. Procedures for establishing such reference densities have been developed empirically over many years and standardized with the test procedures of AS 1289.5.1.1, AS 1289.5.2.1, AS 1289.5.5.1 and AS 1289.5.7.1. In each of the above procedures, a ‘m aximum’ density is obtained (in AS 1289.5.5.1, a ‘minimum’ dry density is also obtained). It must be appreciated that these do not represent the maximum (or minimum) achievable, but that which can be achieved using the test procedures specified.
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7.4 SAMPLE SELECTION FOR REFERENCE DENSITY
For routine compaction testing, the sample for determination of the laboratory reference density (see Clause 7.3) should be obtained in accordance with AS 1289.5.4.1 or AS 1289.5.7.1. NOTE : The sam ple wil l comp rise eit her the materi al recover ed from the field densit y determinations or from that volume of material considered in the field density determination as in the case of testing using nuclear gauges. In most instances, the amount of soil will be insufficient to allow satisfactory completion of the laboratory reference density test. In such circumstances, additional material should be recovered immediately from around the zone in which the field density determination was made and over the full depth considered in that determination, but no deeper. The sides of any excavation made to recover such material should be approximately vertical. . ) 1 2 1 3 5 0 0 1 (
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The sample for the laboratory reference density test should be taken from the compacted material immediately after (or during) the field density determination. Only when it has been established that the influences of field compaction do not affect the value of the laboratory reference density, is it appropriate to sample from the stockpile or the test area prior to compaction. AS 1289.5.4.1 and AS 1289.5.7.1 require that a laboratory reference density v alue be determined for each field density determination. The requirement for a laboratory reference density test for each field density should apply equally to any retest of an area, whether such retesting be required after previous testing has indicated inadequate compaction and further compaction has been carried out, or whether merely checking compaction after some period of time but without further work having been carried out on the area. 7.5 USE OF DIFFERENT TEST PROCEDURE
In general, the test procedure for determination of relative compaction should not be varied for a given soil type by using more than one test procedure for either field density or reference density. In particular, control of moisture content, relative to optimum moisture content determined in accordance with AS 1289.5.7.1, should not be included with or compared to those determined in accordance with AS 1289.5.1.1 and AS 1289.5.2.1, as different results may be obtained. The use of different test procedures may be misleading for some clays of high plasticity. In certain circumstances, alternative testing strategies may be appropriate, e.g., in the case of verifying deep compaction achieved by impact rollers or impact compaction. Trial programs may be required to develop the most appropriate testing regime for any particular project or site. 7.6 PERMISSIBLE OVERSIZE
AS 1289.5.1.1 and AS 1289.5.2.1 restrict the maximum particle size in the test specimen to 37.5 mm. Many engineering materials contain a proportion of larger material, which can be accommodated in the field density determination, provided appropriate test procedures are followed. AS 1289.5.4.1 and AS 1289.5.7.1 prov ide a basis for adjusting the reference density to make allowance for the presence of this oversize material in the field and its exclusion from the laboratory reference density test. 7.7 PREPARATION OF LABORATORY REFERENCE DENSITY SAMPLES
All samples for laboratory reference density testing should be prepared in accordance with AS 1289.1.1. This requires the soil to be prepared over a 10 mm screen.
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It is generally accepted that to establish repeatable well-conditioned laboratory compaction curves in heavy clay soils (see AS 1289.5.1.1 and AS 1289.5.2.1) up to one week of moisture curing of each subsample for the compaction test may be required. Lesser curing times are required for lower plasticity clays, sandy clays and the like; however, for routine compaction control testing, rarely is it practical to permit such curing time. Where such curing is not undertaken, the implications of poorly conditioned curves should be taken into account. In particular, the influence of differential moisture within the test samples and the potential for shifts in the apparent compaction characteristics of the material should be recognized (see AS 1289). The time allowed for moisture conditioning relies upon experience and judgement. Consequently, it can be expected that variability in test results will occur and should be allowed for in the specification if deviation from the requirements of AS 1289 is to be tolerated. Test reports should include the curing procedures and sample preparation procedures adopted.
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The Hilf rapid compaction method (see AS 1289.5.7.1), allows the test to be performed provided the added moisture value is between −4% and +6%. For materials with moisture contents outside these limits, curing for a prolonged time will generally be necessary and the maximum dry density and optimum moisture content need to be determined in accordance with AS 1289.5.1.1 or AS 1289.5.2.1, as appropriate.
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S E C T I O N
8
I N S P E C T I O N
AS 3798 —200 7
A N D
T E S T I N G
8.1 GENERAL
To assess whether the quality of materials and workmanship provided on a project are consistent with the design requirements, the earthworks for a project should be inspected and tested at regular and appropriate intervals, having regard to the nature of the work, its required function and the specification. The specification should detail the level of inspection and testing required as detailed in Clauses 8.2 and 8.3. Adequate control of earthworks will require appropriate inspection and should not rely on test results alone. These inspection measures may include visual assessment of fill or foundation materials, test rolling, surveillance of compaction procedures and compaction trials. Relative compaction testing may be supplemented by other testing.
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8.2 LEVEL 1 INSPECTION AND TESTING
The primary objective of Level 1 Inspection and Testing is for the geotechnical inspection and testing authority (GITA) to be able to express an opinion on the compliance of the work. The GITA is responsible for ensuring that the inspection and testing is sufficient for this purpose. The GITA needs to have competent personnel on site at all times while earthwork operations are undertaken. Such operations include the following: (a)
Completion of removal of topsoil.
(b)
Placing of imported or cut material.
(c)
Compaction and adding/removal of moisture.
(d)
Trenching and backfilling, where applicable.
(e)
Test rolling.
(f)
Testing.
The superintendent should agree on a suitable inspection and testing plan prior to the commencement of the works. On completion of the earthworks, the GITA will usually be required to provide a report setting out the inspections, sampling and testing it has carried out, and the locations and results thereof. Unless very unusual conditions apply, the GITA should also be able to express an opinion that the works (as far as it has been able to determine) comply with the specification and drawings. A1
8.3 LEVEL 2 SAMPLING AND TESTING
A geotechnical testing authority (GTA) will be appointed to carry out sampling and testing as required or specified. The GTA is responsible for selecting the location of sampling and testing operations within each visit made to the site. The superintendent is responsible for advice as to when such visits are required and is responsible for ensuring that sufficient samples and tests are taken ov er the project. On completion of the earthworks, the GTA may be required to provide a report, setting out the sampling and testing it has carried out, and the locations and results thereof. The GTA will not be in a position to express any opinion beyond this as to the compliance of the works with the specification or their suitability for any particular purpose.
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8.4 GEOTECHNICAL INSPECTION AND TESTING AUTHORITY (GITA)
The GITA should have the necessary independence, equipment and competence to be able to undertake all inspections and testing called for. Inspections and testing should be carried out by competent personnel experienced and knowledgeable in earthworks, materials and have a sound understanding of the implication of the specification requirements, e.g., geotechnical professional, geotechnician experienced in earthworks or an inspection authority accredited in accordance with ISO/IEC 17020 to perform such earthworks inspections.
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The GITA may provide on-site field density and moisture content testing and sampling of earthwork materials. It is unlikely (except for very small projects) that the inspector of the works will be able to adequately fulfil this function and undertake the necessary laboratory reference density testing. Such reference density testing may be undertaken offsite or separately by a dedicated site laboratory. A1
A GITA may also operate as a GTA where only Level 2 sampling and testing is specified. 8.5 GEOTECHNICAL TESTING AUTHORITY (GTA)
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The GTA should have the necessary independence, equipment and competence to be able to undertake all testing called for. The GTA should perform all sampling and testing both on site and at the laboratory. When the earthworks site is remote from a central testing laboratory, in order to assist in the timely production of the test results, a laboratory may be established on site. On very large projects, the amount of laboratory testing required may require separate staff to perform field testing and laboratory testing. 8.6 STATEMENT S OF COMPLIANCE
Having regard to relevant State regulations, the superintendent may request suitable statements of compliance to specifications and codes at the time of employing a GITA. In cases where a GTA is employed for Level 2 supervision only, the statement of compliance is the responsibility of the superintendent. 8.7 FREQUENCY OF TESTING
Testing is expensive and time-consuming; therefore, the frequency and extent of testing should be carefully chosen, in conjunction with test rolling, to assess the compliance of completed work without adding unnecessary costs or delays. Such testing should be carried out by competent personnel experienced in earthworks testing. The project may require that the testing authority be accredited in accordance with ISO/IEC 17025 to perfor m the testing. The precise scope of services to be provided by the GITA or the GTA may differ from one contract to another and, therefore, should be ascertained before work begins. A testing strategy established at the commencement of work may be reassessed if a high degree of uniformity becomes evident during construction. A guide to the required frequency of testing for earthworks projects, to which this Standard is applicable, is given in Table 8.1. In variable or difficult conditions, more frequent testing may be required. These testing frequencies relate to acceptance on a ‘not one to fail’ basis, and may n eed to be varied if statistical control techniques are employed (see Appendix C). For projects requiring more than just a few tests to check compliance, the testing should essentially be carried out in a number of randomly chosen locations and at the frequencies given in Table 8.1. However, for small projects, it may be appropriate to undertake testing in specific locations, based on visual appearance or past experience (e.g., compaction may be more difficult to achieve adjacent to access holes, kerbs or over backfilled service trenches). ©
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It should not be assumed that a test result applies only to the area immediately surrounding it. Where any test in a lot (see Clause 1.2.8) indicates that compliance with the specification has not been achieved, the lot is considered to have failed. On this basis, the entire lot needs to be reworked and retested. Selection of a lot for testing requires careful consideration. TABLE 8.1 FREQUENCY OF FIELD DENSITY TESTS Type of earthworks Type 1 Large scale operations (greater than 1500m 2 e.g., subdivisions, large industrial lots, road embankments) . ) 1 2 1 3 5 0 0 1 (
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Frequency of tests (see Note 2) 1 test per layer per material type per 2500m 2; or 1 test per 500m 3 distributed reasonably evenly throughout full depth and area; or 3 tests per lot (Clause 1.2.8) Whichever requires the most tests
Type 2 Small scale operations (e.g., individual residential lots)
1 test per layer (see Note 3) per 1000m 2; or 1 test per 200m 3 distributed reasonably evenly throughout full depth and area; or 1 test per residential lot per layer Whichever requires the most tests
Type 3 Concentrated operations 1 test per layer (see Note 3) per 500m 2; 2 less than 500m (e.g., back filling of or small farm dams, gullies and similar) 1 test per 100m 3 distributed reasonably evenly throughout full depth and area; or 3 tests per visit Whichever requires the most tests
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Type 4 Confined operations (e.g., filling behind structures) (see Note 4)
1 test per 2 layers per 50m 2
Trenches
1 test per 2 layers per 40 linear metres
NOTES :
A1
1
The above guidelines refer to the determination of relative compaction using a direct method; however, where an indirect method is used, e.g., Perth sand penetrometer (AS 1289.6.3.3), some interpretation of the guidelines may be required.
2
Tests in areas of uncertain compaction and retests of failed areas should be carried out. These are additional to the testing recommended in this Table.
3
Where Level 2 sampling and testing has been specified it may be acceptable to test more than one layer per site visit, by excavating to the test level. When testing a layer that has already been overlain by additional earthworks, the test site should be prepared by scraping off the overlying layer(s) and preparing a suitable pad for testing as required by AS 1289.5.3.1, AS 1289.5.3.2 or AS 1289.5.8.1.
4
Implies hand-operated or small equipment.
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APPENDIX A
REFERENCED DOCUMENTS AS 1289 1289.1.1 1289.1.4.2 1289.5.1.1 . ) 1 2 1 3 5 0 0 1 (
1289.5.2.1
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1289.5.3.1 1289.5.3.2
1289.5.3.5 1289.5.4.1
1289.5.5.1
1289.5.6.1 1289.5.7.1
1289.5.8.1
1289.6.3.2
1289.6.3.3 1289.6.5.1
1726
Geotechnical site investigations
2870
Residential slabs and footings—Construction
4482
Guide to the investigation and sampling of sites with potentially contaminated soil Part 1: Non-volatile and semi-volatile compounds
4482.1
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Methods of testing soils for engineering purposes Method 1.1: Sampling and preparation of soils—Preparation of disturbed soil samples for testing Method 1.4.2: Sampling and preparation of soils—Selection of sampling or test sites—Stratified random number method Method 5.1.1: Soil compaction and density tests—Determination of the dry density/moisture content relation of a soil using standard compactive effort Method 5.2.1: Soil compaction and density tests—Determination of the dry density or moisture content relation of a soil using modified compactive effort Method 5.3.1: Determination of the field density of a soil—Sand replacement method using a sand-cone pouring apparatus Method 5.3.2: Soil compaction and density tests—Determination of the field dry density of a soil—Sand replacement method using a sand pouring can, with or without a volume displacer Method 5.3.5: Soil compaction and density tests—Determination of the field dry density of a soil—Water replacement method Method 5.4.1: Soil compaction and density tests—Compaction control test— Dry density ratio, moisture variation and moisture ratio Method 5.5.1: Soil compaction and density tests—Determination of the minimum and maximum dry density of a cohesionless material— Standard method Method 5.6.1: Soil compaction and density tests—Compaction control test— Density index method for a cohesionless material Method 5.7.1: Soil compaction and density tests—Compaction control test— Hilf density ratio and Hilf moisture variation (rapid method) Method 5.8.1: Soil compaction and density tests—Determination of field density and field moisture content of a soil using a nuclear surface moisture-density gauge—Direct transmission mode Method 6.3.2: Soil strength and consolidation tests—Determination of the penetration resistance of a soil—9 kg dynamic cone penetrometer test Method 6.3.3: Soil strength and consolidation tests—Determination of the penetration resistance of a soil—Perth sand penetrometer test Method 6.5.1: Soil strength and consolidation tests—Determination of the static cone penetration resistance of a soil—Field test using a mechanical and electrical cone or friction-cone penetrometer
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ISO ISO/IEC 17020 17025
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General criteria for the operation of various types of bodies performing inspection General requirements for the competence of testing and calibration laboratories
AUSTROADS NTR-09 Pavement materials: statistical assessment of quality
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APPENDIX B
TYPICAL SITE RECORD SHEETS This Appendix sets out typical site records, which may be appropriate to keep in respect of the earthworks undertaken for projects to which this Standard applies; however, each project will have its own specific needs, which should also be addressed. Modifications to the given examples may be necessary to suit individual requirements. DAILY GEOTECHNICAL REPORT
NAME OF ORGANIZATION PREPARING SHEET:
Sheet No.: Date:
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Job No.: Project: Owner:
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Constructor: Superintendent: Inspection and testing by (GITA/GTA): Level 1 or 2: GITA/GTA retained by: Earthworks in current progress:
Materials testing: Refer to material, type, source, purpose of testing, sampling methods and locations, test types, sample reference numbers, results obtained, and to whom distributed.
Field density testing: Refer to types of test, section of work to which tests apply, test locations and levels, test reference numbers, results obtained, and to whom distributed.
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DAILY GEOTECHNICAL REPORT
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( continued )
Laboratory compaction testing: Refer to test methods, location of sampling, sample reference numbers, results obtained, and to whom distributed.
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d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
Works meeting geotechnical requirements: Refer to work type (e.g. stripping, subgrade compaction), basis of assessment (e.g. inspection, test reference numbers, and the like), extent of works apparently complying and requirements met.†
Works failing to meet geotechnical requirements: Refer to work type (e.g., stripping, subgrade compaction), basis of assessment (e.g., inspection, test reference numbers, and the like), extent of work apparently failing to comply, requirements not met, action taken (instructions issued, retests ordered, and the like)†.
Remarks: Include observations on works, site conditions, meetings or conversations on site, and the like.
SIGNED: †
POSITION:
DATE:
As appropriate
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SITE TESTING RECORD
NAME OF GEOTECHNICAL TESTING AUTHORITY:
Sheet No.: Date: Job No.:
Project: Owner: Constructor: Superintendent: Level 1 or 2: GTA retained by: Testing requested by:
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d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
Weather:
Earthworks in current progress:
Sections of work presented for testing:
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SITE TESTING RECORD
AS 3798 —200 7
(continued )
Sampling/Testing carried out: Refer to material types, sources, methods of sampling and field testing, locations and levels of sampling and field testing; test and sample reference numbers.
Instructions received on site: Nature of instructions, from whom, action taken. . ) 1 2 1 3 5 0 0 1 (
d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
Instructions, advice or results given on site: Nature of instructions, to whom, action observed.
Method of recording locations and/or levels: By whom, reference marks, bench marks, whe re recorded.
Remarks: Include observations on works, site conditions, meetings or conversations on site, etc.
SIGNED:
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POSITION:
DATE:
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EARTHWORKS SUMMARY REPORT
NAME OF ORGANIZATION PREPARING SHEET:
Sheet No.: Job No.:
Project:
. ) 1 2 1 3 5 0 0 1 (
Owner: Constructor: Superintendent:
d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
Level of engagement of geotechnical inspection and testing authority in accordance with AS 3798, Section 8.
Prior usage of project site: Purpose of present development:
Broad description of earthworks undertaken, extent of fill, etc.:
Observations on stripping and site preparation:
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AS 3798 —200 7
( continued )
EARTHWORKS SUMMARY REPORT
Observations of fill materials.
Summary of testing: Refer to attached result certificates, location plans, etc. . ) 1 2 1 3 5 0 0 1 (
d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
Location on site and type of earthworks
Estimated volume m
3
Number of tests Material quality Total
Failed
Field density Total
Failed
Compaction
Action taken where non-com pli ances occurred
Remarks: Note—Unless engaged at Level 1 (see AS 3798 Clause 8.2) a testing authority is not in a position to express an opinion as to whether the works comply with the drawings or specification or are suitable for a particular purpose.
Signed: ___ _________ ____________ _________ ______
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APPENDIX C
STATISTICAL METHODS IN EARTHWORKS C1 GENERAL
Earth materials are inherently variable and, whilst working from borrow to fill often acts to reduce the variability, compacted fill is also variable. Thus the density and moisture content of a fill will vary from any one location to other locations, even if considerable care is taken to attempt to achieve a uniform result. The ‘not any to fail’ specification commonly applied to small earthwork projects is based on a successful history of producing suitable fills and only indirectly accounts for the inherent variability. So-called ‘statistical’ methods have been applied to earthworks, in an attempt to quantify the variability. These methods are used for two general purposes as follows:
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d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
(a)
Quality control (QC ) — to control the process, the contractor uses quality control to provide advance warning of any changes in the earthwork quality so that the method can be changed to ensure continuing satisfactory placement. It can also be used to estimate the in situ properties of the fill.
(b)
Quality assurance (QA)—to ensure that the product (fill) quality is within specification requirements. In this Standard, it is quality assurance that is being considered and two terms require definition as follows: (i)
Owner’s risk (often B) —the risk of accepting fill as having a certain quality when, in fact, it does not.
(ii)
Contractor’s risk (often α) —the risk of fill being rejected as not having a certain quality when, in fact, it does.
The owner’s risk can always be reduced to zero simply by always rejecting the product. There is then no chance of accepting poor quality material. The obvious problem with this is that the contractor’s risk is 100% and good quality material is always rejected. Statistical methods should aim to balance these risks. To reduce both risks simultaneously requires a reduction in the uncertainty regarding the actual quality of the product, which is generally achieved by increasing the number of samples used in decision-making. At present, statistical QA schemes find little application in works within the scope of this Standard. In Australia, such schemes find their main use in larger road construction projects, under the control of state road authorities. In large areas or for large volumes of earthworks, the amount of testing for field moisture content and density may be considerable. More efficient use of testing may be made by applying statistical methods to selection of test sites and to the test results based on lots of work. The publication AUSTROADS NTR-09 provides a working basis for the development of suitable statistical specifications for earthworks covered by this Standard, by the suitable selection of proportion defective, acceptable quality levels and operating characteristic curves.
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AS 3798 —200 7
C2 SELECTION OF TEST SITES IN A TEST LOT SAMPLING
The selection of test sites in a test lot should be as follows: (a)
Stratified random sampling To ensure independence, lots are frequently divided into equal areas or portions called strata. Where the number of sample tests required is known, the lot is subdivided so that one test is selected from each stratum. Random numbers are used sequentially to define the longitudinal and lateral position for each site within each stratum in turn. This process is termed random stratified sampling.
(b)
Systematic sampling Systematic sampling occurs when the longitudinal and the lateral locations of test sites are selected at fixed intervals.
C3 ACCEPTANCE . ) 1 2 1 3 5 0 0 1 (
d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
When using statistical acceptance schemes, the acceptance values are based on characteristic values of the properties, e.g., density ratio. The characteristic values are calculated using the following equation: C = Mean − k × s where C = characteristic value k
= a constant depending on proportion defective, the number of values and the contractor’s risk
s
= standard deviation of the values in the lot for the number of tests performed
Acceptance may be unconditional or conditional as follows: (a)
Unconditional quality acceptance In an unconditional quality assessment system, the choice lies between acceptance or rejection of the product without application of conditions or demand for further treatment.
(b)
Conditional quality acceptance In a conditional acceptance system, work that meets a specification limit is accepted without condition but work just outside the specification limits may be accepted subject to either— (i)
further treatment, and possibly further testing; or
(ii)
adjusted payment.
Suitable k values for different number of tests and different levels of risk are shown in AUSTROADS NTR-09. C4 OUTLIER RESULTS
AUSTROADS NTR-09 provides information on the treatment of outlier results. In cases where a result or results are outliers, it is preferable to retest the lot rather than to adjust the acceptance criteria based on a reduced num ber of samples in order to reduce bias.
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APPENDIX D
SUITABILITY OF COMPACTION EQUIPMENT FOR VARIOUS TYPES OF FILL MATERIALS
Equipment
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Most suitable soils
Smooth wheel rollers, static or vibrating
Well-graded sand-gravel mixtures, crushed rock
Rubber-tyred rollers
Coarse-grained soils with some fines
Grid rollers
Weathered rock, well-graded coarse soils
Sheepsfoot rollers:
d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
Static
Fine-grained soils with more than 20% fines
Vibrating
As for static, sand-gravel mixtures
Vibrating plate (light)
Coarse-grained soils with 4–8% fines
Tampers, rollers
All types
Impact rollers, impact compaction
Wide range of soil types and moisture regimes
NOTE: This Appendix is based on Table 2.3 in Haus mann, Manfred R. (1990), Engineering Principles of Ground Modification. McGraw-Hill.
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AS 3 798— 2007
AMENDMENT CONTROL SHEET AS 3798—2007
Amendment No. 1 (2008)
CORRECTION SUMMARY: This . ) 1 2 1 3 5 0 0 1 (
d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
Amendment applies to the Preface, Section 2, Clauses 4.3, 4.4, 6.1.5, 6.2.6, 8.3 and 8.4, and
Table 8.1. Published on 5 August 2008.
AS 3798 —200 7
44
NOT ES
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d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
. ) 1 2 1 3 5 0 0 1 (
d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 9 0 0 2 r e b m e t p e S 7 n o l l e d d e P n o v e B r M o t d e s n e c i L
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