3
H.-J. Bayer (Hrsg.)
HDD-Practice Handbook
Vulkan-V Vu lkan-Verlag erlag · Essen · Germany
Inhaltsverzeichnis
7
Table of contents Preface .... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....
5
1
Introduction ......... .................. .................. ................... ................... .................. ................... ................... .................. .............. .....
13
1.1
Definition Defini tion of the term HDD ........ .................. ................... .................. ................... ................... .................. ........... ..
13
1.2
History Histo ry of drillin drilling g and HDD .......... ................... .................. ................... ................... .................. ................... ..........
13
1.3
Fundamental differences between horizontal and vertical drilling technique techn ique ........ .................. ................... .................. ................... ................... .................. ................... ................... .................. ........... ..
17
2
Technology of trenchless pipelin pipeline e installat installation ion with HDD ..........
19
2.1
Methodology Meth odology of drillin drilling g contr control ol ........ .................. ................... .................. ................... ................... .............. .....
19
2.2
Methodology Meth odology of pipelin pipeline e insta installation llation .......... ................... .................. ................... ................... .............. .....
20
2.3
Range of horizon horizontal tal drillin drilling g syste systems ms .......... ................... .................. ................... ................... .............. .....
21
2.4 2.4.1 2.4.2 2.4.3 2.4.4 2.4.5 2.4 .5 2.5 2.6
Qualified realis Qualified realisation ation of tren trenchless chless pipe instal installation lation projec projects ts ......... ................ ....... Planning Plann ing phase ......... .................. ................... ................... .................. ................... ................... .................. ................... .......... Pipe materi material al contr control ol phase .......... ................... .................. ................... ................... .................. ................... .......... Maschine Masch ine contr control ol phase .......... ................... .................. ................... ................... .................. .................. ................ ....... Constructio Const ruction n phase ......... ................... ................... .................. ................... ................... .................. ................... ............. ... Reworki Rew orking ng pha phase se .... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ...... .. Suitable Suita ble pipe materi materials als .......... ................... .................. ................... ................... .................. ................... ................ ...... Advantages Advan tages of HDD in pipelin pipeline e insta installation llation ......... .................. ................... ................... .............. .....
22 22 23 23 23 24 24 25
3
Soil analysis as a precondition for successful pipe installation ......... .................. ................... ................... .................. ................... ................... .................. ................... ................ ......
28
3.1
Historical Histo rical perspe perspective ctive ......... .................. ................... ................... .................. .................. ................... ................... ........... ..
28
3.2
Early soil inves investigati tigation on in pipe insta installation llation ......... ................... ................... .................. ................ .......
28
3.3
Legal liabili liability ty for soil conditi conditions ons ........ .................. ................... .................. ................... ................... .............. .....
29
3.4
Soil analys analysis is as academ academic ic discip discipline line .......... ................... .................. ................... ................... .............. .....
29
3.5 3. 5
Norm No rms s re regu gulat latin ing g so soil il an anal alys ysis is an and d ma mate teri rial al cla class ssif ific icat ation ion ....... .......... ..... ..... ...... ...
30
3.6
Investigati Inves tigation on criteri criteria a for pipe instal installation lation ........ .................. ................... .................. ................... ..........
30
3.7
The soil: risk and calcu calculation lation factor ......... .................. .................. ................... ................... ................. ........
31
3.8
Soil invest investigation igation ......... .................. .................. ................... ................... .................. ................... ................... ................. ........
31
3.9
Conclu Con clusion sion .... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....
33
4
Comparison of trenchless and open cut construction .. ...... ...... .... ...... ....
4.1
Introductio Intr oduction n ......... .................. ................... ................... .................. ................... ................... .................. ................... ................ ......
34
4.2 4.2.1 4.2.2
Comparative examin Comparative examination ation of constr construction uction method methods s .......... ................... .................. ......... Required Requi red equipm equipment ent and numbe numberr of trans transport port runs ......... .................. ................... .......... Required Requi red const construction ruction time .......... ................... .................. ................... ................... .................. ................... ..........
34 34 36
34
8 4.2.3 4.2.4 4.2.5 4.2.6
Inhaltsverzeichnis
4.2.7 4.2.8
Affected traffiic areas .......................................................................... Noise and dirt factors .......................................................................... Required amount of reinstatement material .......................................... Resource consumption and corresponding disposal site requirements ........................................................................................ Indirect cost .......................................................................................... Installation effects on street paving and pipe service life ....................
36 36 37 37 38 40
5
HDD machine technology ..............................................................
43
5.1 5.1.1 5.1.2 5.1.3 5.1.4 5.1.5 5.1.6
Drilling unit classification ...................................................................... Shaft bore machines.............................................................................. Mini bore rigs ........................................................................................ Midi bore rigs ........................................................................................ Maxi bore rigs ........................................................................................ Mega bore rigs ...................................................................................... Performance limits ................................................................................
43 43 46 46 46 46 47
5.2 5.2.1 5.2.1.1 5.2.1.2 5.2.1.3 5.2.1.4 5.2.1.5 5.2.1.6 5.2.2 5.2.3 5.2.3.1 5.2.3.2 5.2.4 5.2.4.1 5.2.4.2 5.2.4.3 5.2.4.4 5.2.5 5.2.5.1 5.2.5.2 5.2.5.3 5.2.5.4 5.2.6 5.2.7
Main components ................................................................................ Drilling system ...................................................................................... Bore rig ................................................................................................ Slide drill (bore rig, upper part) ............................................................ Undercarriage and stability (bore rig, lower part) ................................ Drive and hydraulic units ...................................................................... Percussive unit ...................................................................................... Safety equipment .................................................................................. Drilling fluid mixing unit and mud pump .............................................. Pipe string (drill rods und bore tools) .................................................. Drill rods ................................................................................................ Drill rod magazine .................................................................................. Bore tools ............................................................................................ Bore heads for pilot bores .................................................................... Upsizing tools (backreamers) .............................................................. Swivels .................................................................................................. Pipe pulling device ................................................................................ Control and detection technique .......................................................... Detection of the bore head .................................................................. Walkover techniques.............................................................................. Wire-Cable techniques .......................................................................... Operating panel .................................................................................... Transport and supply units .................................................................. Recycling unit (optional) ......................................................................
47 48 48 48 48 49 49 49 50 52 52 54 55 55 57 59 59 60 60 60 61 62 62 63
5.3 5.3.1 5.3.2
63 63
5.3.3 5.3.4
HDD accessories .................................................................................. Software for planning, representation and documentation of bores .... Software for soil testing, defining of the drilling fluid and bore tooling .................................................................................................... Software for material and jobsite requirement calculation.................... Pulling force measure and recording and documentation software ....
63 64 65
5.4 5.4.1
Requirements for applying the HDD mega rig technique .................... Transport ..............................................................................................
65 65
Inhaltsverzeichnis
9
5.4.2 5.4.3 5.4.4
Jobsite planning and control ................................................................ Rollers and overbends .......................................................................... Ballasting ..............................................................................................
66 66 67
6
Drilling fluids ......................................................................................
68
6.1
Drilling fluid functions ..........................................................................
68
6.2 6.2.1 6.2.2 6.2.3
Establishing stable boreholes with the HDD method............................ Soil expertise ........................................................................................ Essential basic material: bentonite ...................................................... Complementary requirements during a bore ........................................
68 69 69 70
6.3 6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 6.3.6
Frequent dangers to drilled boreholes and their countermeasures ...... Drilling fluid loss .................................................................................... Drilling fluid run-off .............................................................................. Drilling fluid extrusion .......................................................................... Constriction of a borehole .................................................................... Borehole collapse in loose rock .......................................................... Borehole collapse ................................................................................
70 70 72 72 72 74 75
6.4
Emergency kit ......................................................................................
76
6.5
Drilling fluid handbook ..........................................................................
77
7
Rock drilling technique with low-flow mud motors ..................
78
7.1
Basic features of mud motors ..............................................................
78
7.2
Applications of mud motors in HDD......................................................
79
7.3
Mud motor technique ..........................................................................
79
7.4
Performance characteristics ................................................................
81
7.5
Special features of HDD mud motors....................................................
83
7.6
HDD mud motors for small boring systems ..........................................
84
8
Application range of HDD ..............................................................
85
8.1 8.1.1 8.1.2 8.1.3 8.1.4 8.1.5 8.1.6 8.1.7 8.1.8 8.1.9 8.1.10 8.1.11 8.1.12 8.1.13 8.1.14 8.1.14.1
Installation of supply and drainage lines .............................................. Parallel installations for line networks .................................................. Pressure drainage ................................................................................ Data lines and telecommunication cables ............................................ Data lines for traffic guidance and toll systems .................................... Signal cables alongside long-distance lines ........................................ Inner pipe relining ................................................................................ Crossings, under-crossings and under-river crossings ........................ Installation in rural conservation and green areas ................................ Installation in protected ground ............................................................ Installation of flexible anodes ................................................................ Additional installation of airport navigation lights ................................ Underground heating ............................................................................ Connection service lines to dwellings .................................................. Building connections in hillsides .......................................................... Connections to new buildings ..............................................................
85 85 86 86 87 87 87 88 89 89 89 89 90 90 91 91
10
Inhaltsverzeichnis
8.1.14.2 8.1.14.3 8.1.14.4 8.1.14.5 8.1.14.6
Renewal of connections to existing buildings ...................................... Property connections in creeping and sliding hillsides ........................ Short property connections with Pit boring systems .......................... Property connections in rocky ground ................................................ Advantages of trenchless installations in hillside terrain ......................
91 92 93 93 94
8.2
Water development, hydraulic measures, environmental technology, and irrigation ........................................................................................ Horizontal drinking water wells ............................................................ Horizontal wells for lowering ground water levels ................................ Ground water regulation – ground water elevation .............................. Hydraulic redevelopment ...................................................................... Further contamination redevelopment .................................................. Drainage of moving slopes .................................................................. Drain ...................................................................................................... Irrigation ................................................................................................ Monitoring ............................................................................................ Sensor lines for leakage detection ......................................................
94 94 95 96 96 97 97 98 98 98 99
8.3.1 8.3.2 8.3.3 8.3.4 8.3.5 8.3.6 8.3.7 8.3.8 8.3.9 8.3.10 8.3.11 8.3.12
Special civil engineering, foundations, tunnelling and geotechnical applications .......................................................................................... Geotechnical investigation .................................................................. Anchoring .............................................................................................. Tunnel improvement ............................................................................ Bores for ground freezing .................................................................... Injections................................................................................................ Slope stabilisation ................................................................................ Bores for geotechnical instruments ...................................................... Bores for load settlement .................................................................... Precedent ridge stabilisation ................................................................ Fill base sealing .................................................................................... Soil improvement .................................................................................. Further applications ..............................................................................
99 99 99 100 100 100 101 102 102 103 104 104 105
9
Practical application examples ......................................................
107
9.1
Installation of a cable duct parallel to a motorway ..............................
108
9.2
Installation of a gas line through Holzhausen ......................................
109
9.3
Installation of a desalination sea intake pipe in Cyprus ......................
110
9.4
Installation of a water main under railway tracks ................................
114
9.5
Installation of a HDPE protection pipe under the river Kinzig ..............
116
9.6
Installation of a large pipe bundle under the river Danube ..................
117
9.7
Undercrossing the upper Rhine at 400 m length and 24 m depth ......
120
9.8
Installation of a sewage line (800 mm) underneath the River Oka ........
121
9.9
Rivercrossing through limestone ..........................................................
123
9.10
Installation of several cable ducts in the desert ..................................
124
9.11
Installation of a sewer pipe in the Rhine harbour in Duisburg ............
127
8.2.1 8.2.2 8.2.3 8.2.4 8.2.5 8.2.6 8.2.7 8.2.8 8.2.9 8.2.10 8.3
Inhaltsverzeichnis
11
9.12
Installation of a 450 mm drain pipe into the Baltic Sea ......................
129
9.13
450 meter bore under an airfield ..........................................................
131
9.14
Undercrossing a dune to install a seawater extraction line ................
134
9.15
Installation of a lakewater retrieval pipe under Lake Constance ........
137
9.16
Installation of a drinking water pipe through the mud-flats ................
140
9.17
Anchoring a railway embankment for the construction of a subway tunnel ....................................................................................................
143
9.18
Construction of pedestrian tunnels in Abu Dhabi ................................
146
9.19
Installation of pipelines to a distribution position on Dutch island ......
148
9.20
House connections with steerable boring technique ..........................
151
9.21
Open slope installation in difficult sorroundings ..................................
154
9.22
Rainwater drain sanitation ....................................................................
158
9.23
Installation of a rainwater sewer pipe ND 560 through rock ................
163
9.24
Construction a new gas pipeline across the river Rhoˆne ....................
166
9.25
Installation of a 1100 mm ductile cast iron pipeline ND 600 ..............
170
10
Technical guidelines and quality assurance in HDD ..................
178
10.1
DCA, ISTT and GSTT guidelines ..........................................................
178
10.2
Directives and standards ......................................................................
178
10.3
Guidelines for the practice ..................................................................
179
11
HDD literature ....................................................................................
184
11.1
Publications ..........................................................................................
184
11.2
Documentations by associations, technical rules ................................
187
11.3
Further information on the Internet / Links............................................
188
Index of advertisers ..........................................................................
189
1
HDD-Practice Handbook
13
Introduction
1 Introduction 1.1 Definition of the term HDD During the past few years, an international generic term has been established for steerable horizontal drilling technique that – originating in the US – has gained acceptance in nearly every country worldwide: HDD = Horizontal Directional Drilling. Horizontally steered directional drilling was developed in California in the 1970s and was introduced in Europe in 1986 by the name of ‘controlled horizontal flush drilling technique’. Since the term ”flush drilling technique” was put on a level with ”burying of pipes” in utility technique, the term was attributed to near-surface steerable horizontal drilling which provides a more functional description of the process. Contrary to ”deep and deflected horizontal drilling” that has in the meantime become the term most commonly used in the oil and natural gas industries, this term as well as the international abbreviation of HDD are defined as near-surface installation of pipes, cables, filtering wells, oblong structures and devices, holding systems and others using mobile drilling installations with tilted bore rigs, with three-dimensional detection and control functions, with integrated flush drilling technique and the possibility to upsize created boreholes at random, preferably in reverse mode.
1.2 History of drilling and HDD Around 600 B.C.
In China about 500 m deep vertical bores are possible
Around 1420 B.C. First proof of vertical drilling technique in Europe Before 1495
Leonardo da Vinci invents and constructs the first horizontal drilling machine above ground. It serves to bore wooden logs to produce wooden water pipes. In his lifetime, ten horizontal drilling machines are presumed to have been built ( Figure 1.1 ). Leonardo da Vinci also improves the mechanism of vertical drilling.
Around 1780
Vertical bores up to 300 m deep can be sunk
Around 1850
Wrought iron drill stems, steam engines and diamond bore heads open up new possibilities for drilling
1860 – 1890
Important inventions in vertical drilling achieved a depth of 2000 m around 1890
Around 1910
First roller chisel (toothed roller chisel)
Around 1920
First underground horizontal drilling machines to siphon off light carburetted hydrogen gas (methane) from coal beds of the Ruhr district (machines built by company in Sprockhövel/ southern Ruhr district)
Around 1920
Diesel and Otto engines, electric motors and compressed-air motors, drilling turbines, impregnated diamond-boring tools become available
1938
Depth of 4500 m is reached
1958
Vertical depth of 7700 m is reached
14
Introduction
Figure 1.1: Horizontal directional drilling machine, designed and drawn by Leonardo da Vinci
1962
Field test of first screw type motors (mud motors)
1972
Vertical depth of 9160 m reached
1972
First horizontal bore below Pajara River near Watsonville in California by Martin Cherrington using a tilted vertical directional drilling unit
1972 – 1979
Martin Cherrington and others achieved 36 crossings under rivers and traffic routes
1979
Construction of ”original form” of horizontal bore unit for nearsurface use with flat slanted bore rig for installing pipelines
Around 1980
Start of data collection in drilling technique
1982 –1985
Former Boeing aircraft engineers together with scientists of EPRI (US electric power research institute) develop the boring/cutting ground cut using jets. As a result (made by FlowMole), small HDD units for the installation of 1 kV power cables are developed. The units are equipped with (aircraft) intensifiers to create high pressure for washing, an integrated transmitter-receiver detection technique, highly flexible bore stems and asymmetrical bore heads as well as obtuse, graded reamers.
15
Introduction
1983 – 85
The US Gas Research Institute, Chicago and Charles Machine Works (Ditch Witch) develop a dry horizontal bore unit with position detection. A hydraulic drill rig is combined with a bevelled soil displacement hammer (pneumatic rocket) on a hollow bore stem. A long inclined steering surface on the bore head characterises the dry bore units that years later also work with drilling fluid.
1985
13000 m are reached using deep drilling technique
1986
The first bore in Europe using HDD is carried out on the premises of Karlsruhe research centre. FlowTex as a licensee of FlowMole, founded especially for this purpose, starts professional installation of cables and utility pipes.
1987
First with two, then with four bore rigs HDD technology is employed in the areas of Karlsruhe, Mannheim, Stuttgart, Munich and Hamburg. Mostly, utility pipes for natural gas and drinking water are installed.
1987
First HDD applications in England
1987
Development of the first steerable German dry bore unit (Grundomole) at Tracto-Technik
1989
First bore below office tower block using HDD
1989
Development of first HDD fluid bore unit in Germany (in Ettlingen/KSK and Lennestadt/GrundoJet)
1989
First HDD applications using environmental technologies in the military section of Frankfurt Airport (installation of extraction conduits below the runway)
1989
Simultaneous parallel pulling of several utility cables and pipes
1990
First HDD well sinking for contaminated waste sanitation in Günzburg/Bavaria
1991
Start of HDD large-scale drilling technique using Italian overhead bore rig
1991
Construction of GrundoDrill bore rigs at Tracto-Technik
1991
First HDD application in Brno (Brünn) for Eastern Europe
1991
First high-pressure injections using horizontal drilling technique (proving grounds in open pit of Goitsche near Bitterfeld)
1989–1991
Several HDD companies in Germany are established
1992
Using several HDD units simultaneously, complete local supply units for drinking water and natural gas are built in the newly formed German states within a few months only.
1993
First technical meeting on steered drilling (FAGEBO)
1993
Pulling of new pipes inside old pipes using HDD while filling the annulus at the same time
1994
DCA is founded
1995
HDD installation of firmly connected grey cast iron pipes in Krefeld
16
Introduction
1995
First application of (deep drilling) mud motors for HDD
1995
HDD sanitation of contaminated land using air suction
1996
Removal of slumps using HDD
1996
First handbook on the application of HDD is published
1998
First fully automatic prototype HDD unit tried on Söllingen airfield near Baden-Baden. First HDD installation of clayware pipes.
2001
Development of special HDD mud motors
2002
Installation of horizontal anchors using HDD units in Frankfurt/Main
2002
Rock drilling using hammer bore heads on GrundoPit bore rigs
2003
GW 321 as standard technical regulations for HDD installation of gas and drinking water pipes comes into force
2004
Largest HDD unit in Europe is built in Wenden near Olpe (450-ton unit by Prime Drilling)
Figure 1.2: Substantial differences between vertical and horizontal directional drilling
Introduction
17
1.3 Fundamental differences between horizontal and vertical drilling technique Horizontal directional drilling for trenchless installation of cables and pipes, which has become quite common in the meantime, is quite often compared to the fundamentals of vertical directional drilling as is commonly used for, or to a great extent derived from, the exploration of oil or natural gas. The latter is only true in a few cases; the number of fundamental differences especially for small and medium-sized HDD units is rather high which will be described below. Over 90 % of the HDD units constructed and in use can be classified as small and medium-sized bore rigs (up to a max. pulling force of 25 t) and are basically different from classical drilling technique as to their devicerelated construction as well as their handling ( Table 1.1, Figure 1.2 ). HDD mega bore rigs and vertical directional drilling units only share major technical features, i.e. vertical drill rods can also be used with HDD maxi rigs (from a pulling force of 40 t onwards) and mega rigs; bore heads for rock drilling and flush drilling units also have many common features in HDD mega rig and vertical directional drilling. As concerns mud motors for rock drilling, special low-flow motors have in the meantime been developed for HDD units that show characteristic features distinguishing them from mud motors for oil/natural gas applications. These engineering differences have only just occurred during the past three years. It is important to recognise the special and distinguishing features, which result from a drilling technology that grows more and more powerful and impart and apply them correctly. This correct application determines the technical superiority and marketing success in the sector of new drilling technology. Table 1.1: Fundamental differences between vertical and horizontal directional drilling technique
18
Introduction
Table 1.1: Fundamental differences between vertical and horizontal directional drilling technique (Continuation)
Technology of trenchless pipeline installation with HDD
19
2 Technology of trenchless pipeline installation with HDD Trenchless pipeline installation using the HDD technique is a hydro-mechanical and a mechanical process, it is a steerable, easy, environmentally friendly wet drilling method. This installation method with its near-surface, hydro-mechanical drilling following road bends, too, avoids the conventional technique of pipe installation (with open trenches, disruption of traffic). In the above system, the underground bore works on a combined principle of activity. Drilling is not primarily performed using a conventional mechanical technique but using high pressure, concentrated ground loosening water jets or bore suspension jets that penetrate from nozzles at the tip of the bore head and cause a hydro-mechanical penetration of unconsolidated material. For one, the loosened material is discharged with the suspension backflow along the bore rod, for the other, the unconsolidated material is partially relocated in the vicinity of the drifted bore causing a new, more compact bedding in this area by saving void space. At the same time, the void volume is stabilised with bore suspension that is added to the high-pressure water jets. Mechanical detachment of consolidated material also takes place in the cross section of the bore as a secondary effect. Using the steerable HDD process the mechanical portion of ground detachment work increases. When drilling in rocks using mud motors, mechanical detachment work through the bore head prevails – cooled and supported by bore suspension.
2.1 Methodology of drilling control Both vertical and lateral course control for smaller horizontal directional drilling units is effected by the following two components: Firstly, the bore head is equipped with a built-in transmitter creating an electromagnetic field. This transmitter that is located directly behind the bore head in the soil can be tracked above ground with a detection device (field intensity meter) so that the position of the bore head can be located at all times. Secondly, the bore head itself with its cylindrical body has an asymmetrical construction, a bevelled screw-down face and a lateral bevelled supporting face on the bore head. This lateral slant plane acts as a control surface in that it acts as slant support of the bore head by activating the passive ground thrust during steering on the opposite side of the desired direction of the curve. At any time, the position of the bore head can be retraced both from the indicator on the machine and the detection device that is conducted along the road directly above the bore head. In addition, an especially flexible drill string on small horizontal directional drilling units allows a minimum curve radius of 12 m to be drilled. This wet drilling method can also handle several curves moving in opposite directions. Using small bore units, individual lengths of bore sections of up to 500 m are possible with maximum depths between 8 to 12 m since detectibility of the bore head transmitters is limited to these depths. Smaller units are able to drill any loose sediments using equipment for unconsolidated material and any rock formations using special mud motors. Full course control of larger horizontal directional drilling units at greater depth (usually more than 10 m) is for one effected through the asymmetrical, larger bore head as described above, and for the other through an entirely new detection system based on electro-magnetic precision navigation. The connecting drill rod behind the bore head
20
Technology of trenchless pipeline installation with HDD
that, in this case, must consist of anti-magnetic steel, houses sensors in a few metres’ length in bar-shaped catenation, (mostly magnetometers, accelerometers and gradient sensors) continuously determining the position of the control face, the actual hor izontal drilling direction and vertical inclination. Collected data is permanently transmitted to the control console on the bore rig via a cable running inside the bore rod (mono wire). From here, the entire bore is permanently monitored and fully controlled. When using this cable detection principle, aboveground detections can be dispensed with. Since bore lengths of 2000 m and more can be realised using the larger horizontal directional drilling units, navigation by cable detector must function at any depth (300 m and more). In any depth and distance, the steering precision of this method is always 4 % relating to depth and horizontal deviation. German horizontal directional drilling units from the 10 t-class upward are suited for most geological underground formations; using special mud motors controlled bores through rock are also possible.
2.2 Methodology of pipeline installation At the start of the horizontal directional drilling (HDD) process a so-called pilot bore with the diameter of the bore head is made ( Figure 2.1 ). This pilot bore ends at a given target pit. In this target pit the bore head is removed from the loaded bore rod and a reamer oriented in the reverse direction is attached. This reamer is drawn back all the way through the pilot bore in reverse mode in a rotating and washover action thus upsizing the cross section of the bore ( Figure 2.2 ). If the cross section already allows installation of the desired conduit product pipe, this will be attached directly behind the reamer and drawn into the ground. An internal pipe puller connected to the reamer via a swivel serves to pull in the pipe ( Figure 2.3 ). The reaming diameter of the pilot bore should be at least 30 % larger than the outer diameter of the product pipe in order to have a sufficient amount of bentonite and drillings (swellable mixture of bentonite/soil/clay) in the void available for an all-around an firm embedding of the pipe. For larger pipe diameters and more difficult geological underground conditions, several gradual backreaming processes are required with a spare string of bore rods being attached behind the reamer during interim backreaming. It is only during the last reaming process that the product pipe will be pulled in as well.
Figure 2.1: Using HDD a so-called pilot bore is carried out first
Technology of trenchless pipeline installation with HDD
21
Figure 2.2: As a next step following the pilot bore the cross section of the borehole is upsized using a reamer
Figure 2.3: After backreaming or at the time of upsizing the cross section of the borehole the product pipe is pulled in
Using the smaller bore units (midi rigs) product pipes with outer diameters of up to 600 mm can be installed; using the largest bore units, pipes up to a maximum of 2200 mm can be laid.
2.3 Range of horizontal drilling systems Following the geological and possibly geophysical exploration and following the definition of the product pipe size to be installed and the desired length of the bore section, a horizontal directional drilling unit that suits the project is selected. Companies specialising in trenchless pipe installation very often have available a whole range of different horizontal direction drilling units in widely varying performance classes. This allows the most suitable equipment to be selected for both construction and installation conditions at optimal cost. Since the method of detection, as already explained, relates to the bore depth, larger bore units are equipped with an electronic navigation system that transmits data to the control stand via cable while the smaller units are equipped with bore head transmitters. Horizontal directional drilling units most frequently required are in the 7 t to 20 t performance range of thrust and pulling power as these units are very well dimensioned for the standard work of pipe installation in roads located in residential areas and city centres. Smaller units are often used for longer house service
22
Technology of trenchless pipeline installation with HDD
connections or in very restricted environments, while the larger units are employed for installing pipes, in larger dimensioned under-river crossings, in environment technology and geotechnics, in general technical construction jobs as well as for pipeline and sewer pipe installations. As a rule, the specialist company will always select the equipment best suited for the project after consulting with the customer.
2.4 Qualified realisation of trenchless pipe installation projects After having specified the construction job, after an investigation into the bore path based on geological and possibly combining geo-radar technology and after having selected the bore equipment, the actual construction can be carried out. In order for the task to also comply with future requirements of the ISO 9000 quality standards, all project planning and construction phases will be presented and subsequently described in full detail: 1. Project planning phase (obtaining existing components plan, investigating the bore path, discussing underground obstacles, determining the bore path in detail) 2. Installation product control phase 3. Machine control phase 4. Construction phase (opening of starting and target pits, bore phase, monitoring of safety distance, marking of bore path, welding of installation product, backreaming and pulling in phase of the installation product, closing of pits, site clean-up) 5. Follow-up phase (calibration of line, product pipe reference sample, acceptance protocols) and documentation. During individual project phases the following work steps are to be considered:
2.4.1 Planning phase • Obtaining existing components plan: obtaining any plans of third-party installations for the bore path requested by the customer. Comparing the customer’s projected bore path with the underground conditions by inspecting maps providing information on geology, soil specification and possibly town history. Evaluating expert opinions on subsoil, if available. Site inspections (in some cases together with the customer). Questioning of residents in respect of former buildings or underground fills. • Geological/geophysical inspection of bore paths (checking the customer provided expertise on soil): Inspection and evaluation of any third-party installations. Obtaining special permits. Geological and possibly geophysical inspections into the entire width of the bore path by geological exploration of the surrounding area by the Pürkhauer method and ram core soundings and possibly geo-radar measurements. Drilling conditions through the soil, possible bore obstacles (e.g. rocks, building remains, and others) as well as the actual position of third-party installations by geo-radar, if applicable, are explored. By comparing third-party installations with results of the geo-radar measurements and the detected integration points of pipes, the actual position of the pipes can be marked on the ground surface. • Discussion of underground obstacles, determination of the bore path in detail: The results of the geotechnical underground exploration require an in-depth discussion with representatives of the customer. By linking the results of the exploration with
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service-related parameters given by the customer and bore-related criteria of the contractor, the bore path can be determined in detail. Based on this consultation, starting pits can be marked both on the location drawing and on the ground surface. Bore depth, crossing over and underdrilling of buried cables and pipes plus safety clearances are entered and marked in the same way. Based on this detailed information the type of bore rig to be used, related boring tools and soil-specific bore suspension are determined.
2.4.2 Pipe material control phase • Before an installation product is delivered to the jobsite certificates of quality for cable and pipe material should be to hand. • Irrespective of the above, a visual inspection should be made after delivery; steel pipes also require a physical check. In the event of any damaged material – caused either in production or transport - being detected, such material is either to be returned in full or in part. Photographic documentation of the damage is advisable in any case. • Fastest possible supply of replacement material is to be ensured.
2.4.3 Machine control phase • Installation machines are to undergo daily checks for completeness of their equipment and their maintenance status before starting the construction work. Compliance with the provisions for lighting and safety of the jobsite as well as for machine consumables are to be checked, too. With the help of an equipment checklist, any important parameters can be checked before transporting the machines to their place of operation. • It is advisable to consider technical standards for quality tested materials and components as well as for certification of the vendor at the time of manufacture of the boring machines.
2.4.4 Construction phase • Opening of starting and target pits, other civil engineering: Certified contractors should perform third-party civil engineering work, preferably with permi t. Excavation work near buried cables and pipes, proper storage of the excavated soil, securing of excavation pits and their cleanliness require permanent monitoring. • Boring: This service portion is in the exclusive responsibility of the horizontal directional drilling contractor. Before starting the bore, detection instruments are to be calibrated and bore and mud are to be checked for optimum composition or optimised at this time, if applicable. During the bore, results of bore path drill log data should be observed at all times, safety distances, e.g. buried cables and pipes to be crossed, should be continuously taken into account. Unforeseen emergencies requiring change can only be met after having contacted the customer at least by telephone unless possible alternatives have already been agreed upon in advance. During the bore, the course of the bore is to be marked on the road or surface and to be precisely documented in the test certificate (bore protocol). When the bore
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Technology of trenchless pipeline installation with HDD
head comes up in the target pit, high-pressure nozzles should be switched off in time. • Welding the installation product: As a matter of principle, welding of product pipes may only be carried out by authorised expert companies (with certificates) or by specially trained employees. Exceptions are only possible for non-utility cables and pipes. A welding engineer or a qualified welder on site must oversee all welding. Weld parameter protocols are to be made of any welding (normally done by the protocol plotter on the welding machine) and data to be safely stored for later use. • Reaming and product installation phase: This part of the project, too, is the complete responsibility of the trenchless installation contractor. In this case, bore and mud controls are also to be performed before starting the work. The distance of the pilot bore is to be backreamed once or several times in accordance with the desired cross section of the pipe and the product pipe to be pulled in during the last reaming or hole cleaning process. Before pulling in the product pipe, make sure that the pipe string layout is performed in such a way as not to obstruct traffic. The actual process of pulling in the pipe is to take place avoiding friction as far as possible; sliding rollers and cable guide pulleys must be installed without offset bends and with minimal drag. As part of the completely installed pipe the initial piece is to be recovered as reference sample. Drilling fluid from starting and target pits is to be collected by specialist companies providing proof of safe disposal. Pits themselves should be cleaned of drilling fluid. Tools used for reaming are to be checked for abrasion and wear. Technical maintenance and repair is required from time to time • Closing of pits, cleaning of site: This task should be performed by the same contractor who opened the pit. This is required for reasons of quality assurance and liability. When refilling the pits with excavated soil (if suitable) and classifying residue any applicable technical regulations are to be strictly complied with in order to make sure that any damage possibly occurring at a later date cannot be attributed to trenchless bore technique. Thorough cleaning of the site is to be ensured as adverse visual effects could also leave a negative impression on using the trenchless technique.
2.4.5 Reworking phase • Following completion of the construction work, pipes installed in the underground services system or the ordnance survey system need to be updated. Together with depth profile data the actual course of the bore, not the projected one, is to be entered in the as laid plan (using CAD if possible). Any available recorded data should also be archived and a set of copies delivered to the customer. During final inspection together with the customer for the purpose of preparing the bill of quantities, the acceptance and bore protocols should be delivered, too. A reference sample of the product pipe should also be handed over to the customer.
2.5 Suitable pipe materials Using the mini and midi horizontal directional drilling units, nearly any pipe products that can withstand axial pulling and pushing forces, can be installed, for instance: • Communication, transmitter and control cables • Electric cables
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• Polyethylene (PE) and polypropylene (PP) ductwork • Thin-walled steel pipelines • PE or PP water pipes • Natural gas pipes made of PE-HD • Flexible district heating pipes with a maximum of 220 mm OD (outer diameter) • Drain pipes with slotted, perforated or porous surfaces up to 355 mm as well as bundled services with a maximum of six ducts with 50 mm Ø or five with 63 mm Ø • Cast iron pipes with socket joints actuated by thrust up to 144 mm OD. In addition to the types of pipe material mentioned above the followings types can also be installed using the large horizontal directional drilling units with lengths and outer diameters of the pipes relating to the HDD unit size. For mega rigs the below mentioned diameters do not constitute the upper limit. • Cast iron pipes with socket joints actuated by thrust up to 842 mm OD • Steel pipes up to 820 mm OD • Flexible plastic pipes up to approx. 1400 mm OD • Bundled services with an overall maximum of 1400 mm OD • Horizontal well filter pipes • Steel bars and ground anchors for stabilisation.
2.6 Advantages of HDD in pipeline installation The most striking advantage is the preservation of the road or ground surface as static/dynamic supporting structure as there is no trench dividing the road into halves that react physically in different ways; on the contrary, thanks to trenchless underground pipe installation the strong supporting function of the road surface and supporting layers beneath as well as undisturbed soil are preserved completely. The pipe can be embedded firmly. It can even be embedded firmly all-around as the embedding medium usually consists of swellable clays (bentonite), the re-swelling capacity of which in the near-pipe environment (above, on the sides, below) ensures an even and smooth all around support. Selective loads cannot occur in the immediate vicinity of the pipe from the start, if pipes are embedded in the correct, professional way. If handled correctly, trenchless installation of pipes offers the best possible prerequisites for an extended pipe life. The natural structure of the soil all around the pipe installed underground is completely preserved. An even ground drilled in duct form based on optimum static calculation and preserved in its cohesive structure ensures even static loads above and around the pipe so that point loads are completely avoided with firm pipe embedding already discussed. The pipe is installed in a round borehole. Due to the cylindrical geometry of the borehole or the micro tunnel, respective tensions active in the soil will be diverted almost ideally around the cylinder in arch form, as the untouched superstructure has a very good strong supporting effect. Solid filling of the annulus between pipe and cylindrical hollow bore ensures an even better diversion of the mechanical line of tension in the soil. Compressive strain and tensile stress are relatively balanced. If
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Technology of trenchless pipeline installation with HDD
pipes are covered in accordance with regulations, the load on the pipe is decidedly lower than with open trench constructions. By preserving the natural structure of the soil almost no soil exchange will be necessary. Removal of excavated soil will not be required except for minimum quantities at the starting and target pits. At the same time, storage space for sand, pebble stones and crushed backfill material is saved, as the use of these natural resources is extremely low due to the non-invasive way of construction. As the removal of excavated spoil and the transport of the above mentioned resources are kept to a minimum, residents will not be annoyed as a result of high traffic and noise and there will be no obstructions of traffic routes. A construction site that is almost independent of weather conditions also allows high working speeds so that only a fraction of the time (only a quarter in some instances) will be required for trenchless pipe installation work as compared with open trenching. In trenchless construction, installation depths have no influence on the cost since the only factors determining cost are boring and backreaming. The installation of pipes to be laid at great depths can be carried out especially cost effectively using horizontal directional drilling. With horizontal directional drilling using mega rigs, bores under busy traffic routes (roads, railways, waterways, runways for take-off and landing) using mega rigs do not cause any short-term traffic restrictions; with standard drilling technique there will only be very short-term and almost selective delays during detection of the pilot bore. As this is an ongoing process, traffic flows are normally restricted to a few minutes only. In hillside locations in which any conventional open cut pipe installation requires special effort and expense, horizontal drilling technique works with nearly the same bore speed as on flat terrain. Under valuable flora and fauna, in parks, under rows of trees or habitats, horizontal directional drilling does not impair the natural cover in any way as roots can always be crossed underneath without any problem and without additional cost. The same applies to plants on riverbanks when crossing under rivers. Since the bore head can be positioned and steered from the ground surface via a magnetic field sensor, direct steering of the bore path is possible. This allows a flexible reaction to obstructions to be passed under or crossed over; also, buried pipes and cables (e.g. for water, gas, telephone) that might not be buried exactly in the depth and position as indicated in the installation plans can be avoided. This requires prior location of the pipes and cables already installed. For power lines the bore head used in the HDD process is equipped with a kind of warning system. It is only after examination of all consequential costs over a longer period of time that a clear advantage can be noticed which, unfortunately, is hardly ever considered when directly comparing open cut trenching and no-dig Trenchless methods of pipe installation. Especially in case of sealed surfaces, consequential damage can be avoided that usually occurs during the second or third year following an open trench installation and that presents a financial strain on the authorities responsible for road maintenance, i.e. local and district governments as a rule. Here, we refer to damage caused by cracks, open cut and settling mostly appearing over the marginal areas of formerly open trenches and resulting from different physical behaviour of old, new and once again existing surface materials. These consequential costs incurred by local,
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district or federal state governments or public agencies as authorities responsible for road maintenance can be avoided when using horizontal directional drilling. Horizontal directional drilling with mega rigs, moreover, allows major transmission installation measures in a most expedient way, but also inner-city pipe installations of larger dimensions and higher pipe weights are possible. Pipe products made from heavy material (ductile cast iron, steel, thick-walled PE or PP) as well as installation lengths at several meters in depth or heavy, even rocky subsoil can be most expediently handled by mega rigs and are much more attractive both from a technical and economic standpoint as compared with the open trenching method. Especially for the installation of gradient drain pipes characterised by considerable depths employing the HDD method using mega rigs even in less densely populated areas and for new developments of residential areas is attractive, since the lower degree of technical and ecological complexity usually translates into lower cost.
Horizontal Drilling International SAS
Taking care of your pipeline and the environment Since its inception in 1984, HDI expertise in Horizontal Directional Drilling projects has contributed to successes in over 35 countries, with more than 1500 completed large crossings. HDI has the skills and equipment to perform crossings through alluvial soils and many types of rock, for lengths up to 2000 meters and for diameters up to 48". Rigs of 2500 kN pulling capacity and of 150 KNm torque
Wide range of Applications: Water – Gas – Oil – Optic fiber – Electricity … Immeuble Le Guillaumet 60, avenue du Général de Gaulle 92800 Puteaux - France Tel. +33.1.55 91 09 09 - Fax. +33.1.55 91 09 05
[email protected] - http://www.hdi.fr
