Method Statement of Soil Investigation

Soil Investigation for Vietnam King-Whale Project

Method Statements

May, 2007

Contents Figures..................................................................................................................................... II Tables....................................................................................................................................... II 1. Introduction.............................................................................................................. 1 2. Work Plan ................................................................................................................. 2 3. Work Procedure ...................................................................................................... 5 3.1 Soil Boring ........................................................................................................ 5 3.2 Standard Penetration Test and Sampling...................................................... 5 3.2.1 Sampler .................................................................................................. 5 3.2.2 N - value (Blows Count) Record ....................................................... 5 3.2.4 Sampling................................................................................................ 6 3.3 Undisturbed Sampling..................................................................................... 6 3.4 Core Drilling..................................................................................................... 7 3.5 Field Testing...................................................................................................... 7 3.5.1 Field Permeability Test.......................................................................... 7 3.5.2 Observation Well and Piezometer ....................................................... 7 3.5.3 Field Vane Shear Test .......................................................................... 10 3.6 Laboratory Testing ......................................................................................... 10 4. Quality Control...................................................................................................... 11 4.1 Drilling............................................................................................................. 11 4.2 Sampling / Storage ......................................................................................... 11 5. Safety and Environmental Protection Requirement .................................... 13 Appendix A Relative ASTM Standards ................................................................. 14

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Figures Fig 1

Plan Location..................................................................................................1

Fig 2

Observation Well Details ..............................................................................8

Fig 3

Piezometer Stand Pipe Type Details ...........................................................9

Tables Table 1

Boring Scheme for Phase 1 ...........................................................................3

Table 2

Boring Scheme for Phase 2 ...........................................................................4

Table 3

Laboratory Testing Standard Methods ........................................................10

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1.

Introduction The proposed site, as shown in Figure 1, is including two areas as Phase 1 and Phase 2. In order to

get the geological data for detail design, the soil investigation shall be carried out. The geotechnical investigations shall be implemented according to the following description and the specifications in this statement.

PHASE 1

PHASE 2

Figure 1 Plan Location

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2. Work Plan The quantities of boring for Phase1 and Phase 2 are shown in Table 1 and Table 2 respectively. The execution of soil investigation mainly contains two parts: field exploration and laboratory testing. The primary items are listed below and described in detail in the following section. (1) Field Exploration: (a) Boring and Sampling: Drilling, Split Spoon Sample and Thin Wall Tube Sample. (b) Field Testing and Measurement: Standard Penetration Test (SPT), Field Permeability Test, Observation well, Piezometer and Vane Shear Test. (2) Laboratory Testing: (a) Soil Physical Properties: Unit Weight(?t ), Water Content(wn), Specific Gravity(Gs), Soil Grain Size Analysis and Atterberg Test. (b) Soil Shear Strength Test (c) One-Dimensional Consolidation Test.

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Table 1 Boring Scheme for Phase 1 Sample Number Field Testing Propose Bore Borehole Split 3"f Thin Field Vane Soil SPT Observation Hole Depth spoon Wall Permeability Piezometer shear Physical Testing Well No. Sample Tube Test test Properties (set) (m) (set) (set) (set) (set) (set) (set) (set) BH-1 BH-2 BH-3 Total

250 40 30 320

40 26 20 86

2 2 2 6

40 26 20 86

1 0 0 1

0 0 1(15m) 1

0 1(35m) 0 1

1 1 1 3

*Note: The SPT tests and samples of BH-1 are executed from surface to GL.-60m.

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42 28 22 92

Soil Laboratory Testing Unconfined Triaxial 1-D Compression UUU consolidation Test test Test (set)

(set)

(set)

1 0 1 2

0 1 0 1

1 1 1 3

Table 2 Boring Scheme for Phase 2

Propose Borehole Bore Hole Depth No. (m) RH-1 RH-2 RH-3 RH-4 RH-5 RH-6 RH-7 RH-8 RH-9 RH-10 RH-11 RH-12 Total

60 60 40 40 40 40 30 30 30 30 30 30 460

Sample Number Split spoon Sample (set) 40 40 26 26 26 26 20 20 20 20 20 20 304

Field Testing

Soil Laboratory Testing

Vane 3"f Thin SPT Observation Piezometer shear Wall Tube Testing well test (set) (set) (set) (set) (set) 1 1 1 1 1 0 1 1 1 1 1 1 11

40 40 26 26 26 26 20 20 20 20 20 20 304

0 0 0 0 0 1(15m) 0 0 0 0 0 1(15m) 2

0 0 1(35m) 0 0 0 0 0 0 1(25m) 0 0 2

1 0 1 0 0 0 0 1 0 0 1 0 4

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Soil Physical Properties

Unconfined Compression Test

(set)

(set)

41 41 27 27 27 26 21 21 21 21 21 21 315

0 0 0 0 1 0 0 0 0 0 1 1 3

Triaxial UUU test (set) 0 1 0 1 0 0 0 0 1 1 0 0 4

1-D consolidation Test (set) 1 0 1 0 0 0 1 1 0 0 0 0 4

3. Work Procedure 3.1

Soil Boring Soil borings are made to determine the thickness, texture and order of occurrence of the soil strata as they exist in the ground. Every effort should be made to locate and record the datum elevation at which any change in stratification occurs. The minimum diameter of the boreholes will be 100 mm when undisturbed samples are scheduled to be taken. Earth shall be removed by auger or washing and all samples shall be taken by driving an approved 2-in. OD split-barrel sampler. Each sample as it is removed from the ground should be packed so that it will reach the laboratory (or place of storage) in the condition without loss of water or damage by freezing, heating, breakage of containers or other disturbances in transit. Borings shall be the following type and sizes: uncased borings of sufficient size to accommodate a 2-in. OD split-barrel sampler, a 3-in. thin-wall tube sampler (Shelby tube), or a 3-in. piston-type sampler. The walls of uncased borings shall be adequately supported by a suitable suspension of drilling mud.

3.2

Standard Penetration Test and Sampling Standard Penetration Tests shall be conducted at every change of strata and within a continuous stratum at intervals not exceeding 1.5 meters. A sample shall always be taken in the first 1.5 meters of each boring.

3.2.1 Sampler The sampler shall be a two -inch outside diameter split-barrel sampler, with an inside diameter of one and three-eighth (1-3/8) inches. The dimensions of the sampler shall conform to those shown in the Method for Penetration Test and Split-Barrel Sampling of Soils, ASTM Designation D1586, the latest revision. 3.2.2 N - value (Blows Count) Record The sampler shall be driven with a guided hammer or ram into undisturbed soil below the bottom of the boring after the boring has been cleaned to remove all loose and foreign material. The hammer or ram used to drive the two -inch outside diameter sampler shall weigh 140

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pounds and shall fall freely through a height of 30 -in. The number of blows required to drive the sampler each six inches for a total depth of 18 in. shall be counted and recorded. The record shall clearly show the number of blows for each six inches of penetration. Cumulative numbers of blows will not be accepted. In hard materials requiring more than 50 blows per six inches of penetration, the blows for smaller amounts of penetration shall be observed and recorded with special note of the amount of penetration actually obtained. Once the water table has been reached, particular care must be exercised to maintain the hole full of water or at a level higher than the ground water level preceding and during the standard penetration test. During the removal of the drilling rods, chopping bit and assembly, and insertion of the sampling barrel, a positive inflow of water at the top of the casing shall be maintained. 3.2.3 Sampling Immediately upon removal from the hole, the sampler shall be carefully disassembled and the soil classified. The most representative and least disturbed portion of the sample, shall be tightly sealed and kept in Engineer approved containers. The depth of the change shall be recorded. The containers shall be securely sealed to prevent evaporation of the soil moisture. The jar shall be properly labeled as to boring number, depth of sample, number of sample, and number of blows for each six inches of penetration, or as otherwise stipulated above. The project identification and date of sampling shall be clearly shown on the label. If a soil sample is lost or is found unsatisfactory as to size or condition, a second attempt shall be made to obtain a satisfactory soil sample before advancing the casing to a lower elevation. 3.3

Undisturbed Sampling The undisturbed samples of cohesive materials shall be obtained by thin-wall tube sampler (Shelby tube). The tube to be used shall conform to ASTM D1587, its area ratio shall be no more than l0% and its inside clearance ratio shall be between l.0% and l.5%. Samples shall be obtained by forcing the tube into the soil with continuous pressure. Driving will not be permitted. The hole shall be thoroughly cleaned to its bottom prior-to sampling and all samples shall be taken below the bottom of the casing or below the bottom of the hole, if uncased.

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When very soft soils are encountered and a thin-wall tube sampler is not able to recover an undisturbed smap1e, a piston sampler, with a stationary piston, shall be used; the dimensions of the sample tube remaini ng the same as above. 3.4 Core Drilling When bedrock is encountered, perform continuous core sampling utilizing triple tube core barrel and diamond bits of diameter not less than 50 mm. The individual coring runs shall be limited to a maximum length of 2.0 m. Each coring recovery shall be recorded. All significant actions of the bit, water return and reasons for loss of core shall be recorded in the boring log. Core recovery, RQD and rock logging shall be carried out. 3.5 Field Testing 3.5.1 Field Permeability Test Field permeability test is performed to realize the mobility of water flow through aquifer encountered in BH-1. Water is added to an open-ended pipe casing sunk to desired depth. With constant head tests, constant rate of gravity flow into hole and size of casing of pipe are measured. Pipe casing must be carefully cleaned out just to the bottom of the casing. Clear water must be used or tests may be grossly misleading. The testing procedure should be followed NAVFAC DM7.1. The variation of flow rate with time was monitored and the data were used to obtain soil's permeability k value. 3.5.2 Observation Well and Piezometer The observation wells and piezometers are installed to monitor the distribution and variation of groundwater level and piezometric pressure. The detailed installations are sho wn in Figure 2 and Figure 3. After installation, the groundwater and piezometric pressure shall be measured constantly. During the period of field work, the measurement shall be once every day. After the field work finishes, the measurement shall be twice a week lasting one month.

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Figure 2 Observation Well Details

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Figure 3 Piezometer Stand Pipe Type Details

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3.5.3 Field Vane Shear Test Vane Shear Test is performed in order to obtain the in-situ undraine d shear strength and sensitivity of cohesive soil. Because the test is carried out on site, the problems of sample disturbance and the change of stress condition from field to laboratory can be eliminated. The testing procedure shall be followed ASTM D-2573-94 as shown in Appendix A.

3.6

Laboratory Testing For present planning, the lab test include soil property test and shear strength parameters test. Soil property tests include the unit weight, specific gravity, Atteberg test, water content and soil gr ain size analysis. The test results are used for soil classification according to Unified Soil Classification System(USCS). According to the nearby investigation information, the soil layer is mostly cohesive soil layer. The undrained shear strength parameters are very important to design. The shear strength parameters can be obtained from Unconfined Compression Test and Tri-axial UUU Test. The consolidation test is planned to obtain the consolidation coefficient and coefficient of volumetric compression. Laboratory test work items and method are listed as Table 3. The laboratory testing shall follow the standard methods of testing given below.

Table 3 Laboratory Testing Standard Methods Test Approved Standard

Soil Moisture Content and Density

ASTM D22l6-98

Soil Specific Gravity

ASTM D854-92

Particle Size Analysis of Soil

ASTM D422-63

Classification of Soils

ASTM D2487-98

Soil Atterberg Limits

ASTM D4318-95

Soil

Unconfined

Compressive ASTM D2166-91

Strength Soil

Unconsolidated

Undrained ASTM D2850-95

Triaxial Compressive Strength Soil Consolidation Test

ASTM D2435-96

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4. Quality Control 4.1

Drilling The written record referred to as boring logs or field logs form the basis for determining the soil profile and contributed to an estimate of the quality of the samples and the in-situ conditions. Written records should be accurate, clear, concise, and account for the full depth of the boring. The field logs should contain information and the materials encountered, the number and type of samples obtained, the depth and length of the samples, the percentage of core recovery or recovery ratio, etc. Conditions to be recorded include the following. Ÿ Difficulties in drilling, such as squeezing or caving formations. Ÿ The date, depth, and any condition change of drilling fluid during boring operations. Ÿ The name of project and its location. Ÿ The name and positions of members of the field party. Ÿ Describe the methods of advancing the borehole and the methods for stabilizing the boreholes. Ÿ Record all major changes of soil strata. Ÿ Record the number of the sample and its depth. Ÿ Record of groundwater table before commencing every day.

4.2

Sampling / Storage (1)

Removal of sample from sampling device

After the sampling device has been withdrawn from the borehole, the sampling tube was disconnected from the sampler without shocks or blows. For open-tube samplers, sludge which has accumulated on top of the sample will be removed before the length of the sample is determined. (2)

Labeling samples

As samples are removed from the respective borings, they should be numbered by boring and consecutive order, such as S-1 ~ S-n, for split spoon samples and T-1 ~ T-n for thin-walled shelby tube samples, and by the depth of the respective samples. At the same time, the samples will be identified

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with labels and glue d to the outside of the container with waterproof plastic tape. The field engineer must ensure that each sample is labeled consistency with the data in the field log. (3)

Preservation of samples

Undisturbed samples shall be preserved in sample tubes, and coated with wax and sealed in sturdy containers to protect from changes of water content, shock and vibration. The plastic or rubber caps will be placed over the end of the thin-walled tube and sealed with waterproof plastic tape. After the sample has been placed in a suitable container, such as a wooden box, the annulus shall be between the sample and the cont ainer packing material for additional protection for the sample. All the samples shall be stored in certain space away from sunlight, vibration. After collection of certain amount, the samples shall be transported to the laboratory. (4)

Transporting samples

The distributed samples can be transported in almost any type of container and by any available mode of transportation. The undistributed samples, as a minimum requirement, should be transported in wood container that provides cushioning and insulation for each sample. Samples should fit snugly in each container to prevent rolling, bumping etc., and should be protected against vibration, shock, and temperature extremes.

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5. Safety and Environmental Protection Requirement The local laws of safety and environment protection shall be followed. All persons on site and in works areas shall wear appropriate personal protective equipment. The personal protective equipment includes at least the safety helmet with chin strap. The site shall be kept in a clean, clear and uncluttered condition, free of obstructions and hazards, at all times. All material and equipment shall be set up properly, particularly on access routes. There will be warning signals around the drilling rigs where necessary.

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Appendix A Relative ASTM Standards

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