Microtunneling and Horizontal Drilling: Recommendations

This book includes recommendations prepared by members of the French Society for Trenchless Technology (FSTT), based on their recent national multi-year project. Comprehensive guidelines, techniques and theories in the areas of both microtunneling and horizontal drilling are given, encompassing the fields of application for each method, what investigations should be undertaken, which machines and equipment should be used, how the work should be managed and potential problems that may arise. The recommendations, the analytical methods used and their verification with laboratory and field data should not only improve the rate of success of trenchless projects, but will also be of great value to engineers in other countries, who can compare the results with their own findings and assess the international state of the art.

Table of Contents:
Preface 17 André COLSON Introduction 19 Michel MERMET PART I. MICROTUNNELING 23 Chapter 1. Introduction to Guidelines: Subject and Fields of Application 25 1.1. General introduction of “trenchless technology” 25 1.2. History and characteristics of microtunneling methods 27 1.3. Purpose of the guidelines 28 Chapter 2. Techniques and Theory of Operation for the Installation of Pipes by Microtunneling 31 2.1. General information 31 2.2. Different functions of a boring machine 32 2.2.1. Mechanized excavation of the soil 32 2.2.1.1. Blasting the soil 32 2.2.1.2. Confinement of the face 33 2.2.2. Discharge of excavated earth (or mucking) 34 2.2.2.1. Hydraulic mucking 34 2.2.2.2. Mucking with a screw conveyor 35 2.2.2.3. Pneumatic mucking 36 2.2.3. Guidance and trajectory correction 36 2.2.4. Installation of pipelines by jacking 37 2.3. Various types of pipes 37 2.3.1. Materials used 38 2.3.2. Joints between pipes 38 2.3.3. Resistance capacity of pipes 39 Chapter 3. Summary of Parameters Affecting Work at the Site 41 3.1. Summary of parameters affecting the microtunneling. 41 3.1.1. Rate of penetration 42 3.1.1.1. Duration for pipe jacking only 43 3.1.1.2. Total duration for the installation of a pipe in the ground 46 3.1.2. Alignment deviations 46 3.1.2.1. Human factors 46 3.1.2.2. Technological factors 48 3.1.2.3. Factors linked to the soil 50 3.1.3. Frictional forces 51 3.1.3.1. Principle of analysis for experimental data 52 3.1.3.2. Effect of the overcut 53 3.1.3.3. Impact of the downtimes 54 3.1.3.4. Impact of lubrication 57 3.1.3.5. Impact of misalignment 64 3.1.3.6. Impact of granulometry 64 3.1.4. Stresses at the head 64 3.1.4.1. Presentation of general results 64 3.1.4.2. Influence of blasting and mucking 67 3.1.4.3. Influence of trajectory deviations 68 3.2. Description of the main hitches that can occur when constructing a microtunneling site 69 3.2.1. Blocking of the machine 69 3.2.1.1. Various boulders and obstacles 69 3.2.1.2. Excessive friction 70 3.2.1.3. Abrasiveness of the soil 71 3.2.1.4. Sticking of clay 72 3.2.2. Damaged pipes 72 3.2.3. Surface disturbances 73 3.2.3.1. Settlement caused by the annular space 74 3.2.3.2. Instability of the face, poor balancing of the pressure at the face 74 3.2.4. Excessive roll 75 Chapter 4. Guidelines for Investigations 77 4.1. General approach of the investigations 77 4.1.1. General objectives 77 4.1.2. Progress of the investigations 78 4.1.3. Cost of investigations 79 4.2. Data to be acquired 80 4.2.1. Geological configuration of the site 80 4.2.2. Hydrogeological conditions 81 4.2.3. Geotechnical characteristics of the ground 81 4.2.4. Cavities and artificial obstacles 82 4.2.5. Environmental conditions 82 4.3. Methodology and means of investigation 82 4.3.1. Documentary survey 83 4.3.2. Geophysical investigations 83 4.3.2.1. Objectives 83 4.3.2.2. Usefulness of different methods 84 4.3.2.3. General guidelines 86 4.3.3. In situ boreholes and geotechnical tests 87 4.3.3.1. Objectives of boreholes 87 4.3.3.2. Layout of boreholes 87 4.3.3.3. Types of in situ tests 87 4.3.3.4. Guidelines on the choice of boreholes and tests 88 4.3.4. Geotechnical tests at the laboratory 89 4.4. Contents of the geological record 89 Chapter 5. Guidelines for the Choice of Machines and Attachments 93 5.1. General information 93 5.2. The choice of machines according to their mucking process 94 5.3. Choice of attachments 95 5.3.1. The heads: opening, cutting tools 96 5.3.2. The overcut 98 5.3.3. The crusher 99 5.3.4. Bore fluids 99 Chapter 6. Guidelines for Project Design, Dimensions of Pipes and the Pipe Jacking System 101 6.1. Design of shafts 101 6.2. Calculation of pipe jacking stresses 105 6.2.1. Definition of friction between the soil and the pipes 105 6.2.1.1. General definition 105 6.2.1.2. Specific friction values 106 6.2.2. Experimental results relating to unit friction 106 6.2.2.1. Results of the French National Research Project “Microtunnels” 106 6.2.2.2. Results of other studies 110 6.2.3. Calculation methodology for frictional forces 111 6.2.3.1. Verification of the stability of the excavation 112 6.2.3.2. Ground convergence effect 113 6.2.3.3. Calculation of frictional forces for unstable excavation in granular soil 114 6.2.3.4. Calculation of frictional forces for unstable excavation in cohesive soil 118 6.2.3.5. Calculation of frictional forces for a stable excavation 119 6.2.4. Comparison of various approaches with experimental values 120 6.2.4.1. Calculations-measurements comparison: granular soil without lubrication 120 6.2.4.2. Calculations-measurements comparison: granular soil with lubrication 121 6.2.4.3. Calculations-measurements comparison: cohesive soil without lubrication 123 6.2.4.4. Calculations-measurements comparison: cohesive soil with lubrication 124 6.2.5. Guidelines for the calculation of pipe jacking stresses 124 6.2.5.1. Dynamic friction: non-cohesive soil 125 6.2.5.2. Dynamic friction: cohesive soil 126 6.2.5.3. Additional friction caused by stoppage in jacking 128 6.2.5.4. Stress on the cutter head 129 6.2.5.5. Estimate of the maximum pipe jacking stress 129 6.3. Calculation of the maximum acceptable thrust by the pipes during jacking 130 6.3.1. Calculation principle 130 6.3.2. Permissible stress in the pipes 132 6.4. Calculation of the cross-section of pipes 133 6.4.1. Various verifications of the calculation of the size of pipes 133 6.4.2. General calculation principles: basic Terzaghi model 134 6.4.3. Vertical loads to the soil alone 135 6.4.3.1. The experimental Terzaghi model 135 6.4.3.2. The ATV A161 method 137 6.4.3.3. Leonards’ model 137 6.4.3.4. Guidelines for the calculation of vertical loads 138 6.4.4. Horizontal loads of the ground 140 6.4.5. Surface loads 141 6.4.5.1. Permanent surface loads 141 6.4.5.2. Traffic loads 142 6.4.6. Water pressure: presence of groundwater 145 6.4.7. Permissible stress in the pipes 147 6.5. Bore fluids 148 6.5.1. General information 148 6.5.2. Selection criteria 150 6.5.3. Products used 151 6.5.4. Recycling and processing 152 6.5.5. Implementation at the site 153 6.5.6. Slurry treatment: technical and regulatory aspects 153 6.5.6.1. General considerations 153 6.5.6.2. Current regulations 156 6.5.6.3. Lines for removal of drilling residues 156 6.5.6.4. Prospects for reclamation 158 Chapter 7. Guidelines for the Site Supervision 159 7.1. Guidelines for guidance 159 7.1.1. Necessity of controlling trajectory deviations 159 7.1.2. Guidelines for the measurement of deviations 160 7.1.3. Guidelines for the monitoring of deviations 160 7.1.3.1. Initial adjustments and starting of jacking 161 7.1.3.2. Corrections during jacking 161 7.1.3.3. Adjustment of the overcut 162 7.2. Guidelines on the drilling parameters 162 7.2.1. Avoid instability of the face 163 7.2.2. Avoid excessive thrust on the head and the blocking of the cutterhead 164 7.2.3. Checking the roll 164 7.3. Guidelines on lubrication 165 7.4. Guidelines regarding stoppages during jacking166 7.4.1. Provision for the increase in the thrust during restarting 166 7.4.2. Limit the increase of the thrust during restarting 167 7.5. Data acquisition during the project 167 Chapter 8. Socio-Economic and Contractual Aspects 169 8.1. Social and economic aspects: concept of social cost 169 8.1.1. Value of modern urban sites 170 8.1.1.1. Total cost of the work 170 8.1.1.2. Direct cost 170 8.1.1.3. Overhead cost 170 8.1.1.4. Social cost 171 8.1.2. Traditional urban sites: nuisance factors 171 8.1.2.1. Traffic disruption 171 8.1.2.2. Damage to the environment 172 8.1.2.3. Risk of accidents 172 8.1.2.4. Economic impacts 173 8.1.3. Reduction in nuisance by trenchless techniques 174 8.1.4. Methods for evaluating the social cost 176 8.1.4.1. Methods used in a context other than that of urban sites 177 8.1.4.2. Approaches as part of urban underground sites 179 8.1.4.3. Comparison methodology for the costs of trench and trenchless techniques 181 8.1.5. Other suggestions to reduce the social cost 187 8.1.5.1. Susceptibility maps 188 8.1.5.2. Financial incentives 188 8.1.6. Conclusions 188 8.2. Contractual aspects: objectives and success factors 189 8.2.1. Proper contractualisation of a microtunneling project 190 8.2.1.1. Well defined respective roles 190 8.2.1.2. Appropriate risk management 192 8.2.1.3. Knowledge of the structure and underground use 195 8.2.1.4. Suitable allotment and contracting 195 8.2.2. Establishment of appropriate tender documents and a consultation regulation 196 8.2.2.1. Tender documents based on a defined strategy 196 8.2.2.2. Specifications adapted to every item of the tender documents 197 8.2.2.3. A properly described project 197 8.2.2.4. Correctly sized and adapted products 201 8.2.2.5. Well defined and controlled microtunneling procedures 201 8.2.3. Presentation of compliant and pertinent offers by the contractor 202 8.2.3.1. Appropriate qualifications 202 8.2.3.2. Adequate and adapted references 203 8.2.3.3. A complete and definite technical submission 204 PART II. HORIZONTAL DRILLING 207 Chapter 9. Introduction to Guidelines: Purpose and Fields of Application 209 9.1. General introduction of “the trenchless technology” 209 9.2. History and characteristics of drilling methods 211 9.3. Purpose of the recommendations and fields of application 219 Chapter 10. Techniques and Principles of Operation for Horizontal Drilling 223 10.1. General information 223 10.2. Different stages of horizontal drilling 225 10.2.1. Pilot drilling 225 10.2.2. Reaming 226 10.2.3. Guidance and trajectory corrections 228 10.2.3.1. Walk-over systems 228 10.2.3.2. Downhole systems or wireline steering systems 230 10.2.4. Site organization 230 10.2.4.1. Administrative authorizations 230 10.2.4.2. Access, site installation 230 10.2.4.3. Water 230 10.2.4.4. Slurry transfers 231 10.2.4.5. Work areas 231 10.3. Different types of pipes or conduits 231 10.3.1. Thermoplastic pipelines 232 10.3.1.1. Polyethylene pipes 232 10.3.1.2. Polyvinylchloride pipes 238 10.3.2. Metal pipelines 240 10.3.2.1. Steel pipes 240 10.3.2.2. Pipes in ductile cast iron 242 Chapter 11. Summary of Parameters Affecting the Start of a Building Site 247 11.1. Summary of parameters affecting the execution of horizontal drilling 247 11.2. Parameters related to the ground 247 11.3. Parameters related to groundwater and soil permeability 248 11.4. Parameters related to obstacles 249 11.5. Parameters related to the nature of the pipeline to be installed 249 11.6. Parameters related to the drive length 249 11.7. Parameters related to the radius of curvature 251 11.8. Parameters related to the characteristics of the drilling mud 251 11.9. Parameters related to the characteristics of the drilling rig 251 11.10. Parameters related to the regularity of the profile, the piloting and the guidance 251 11.11. Parameters related to preliminary exploration 251 11.12. Parameters related to the (overall dimensions) congestion of the site 251 11.13. Parameters related to delays 252 11.14. Parameters related to weather conditions 252 Chapter 12. Guidelines for Explorations 253 12.1. General theory of explorations 253 12.1.1. General objectives 253 12.1.2. Stages of explorations 254 12.1.3. Cost of explorations 254 12.2. Data to be acquired 255 12.2.1. Geological configuration of the site 255 12.2.2. Hydrogeological conditions 257 12.2.3. Geotechnical characteristics of the soils 257 12.2.4. Pockets and artificial obstacles 258 12.2.5. Environmental parameters 258 12.3. Methodology and means of explorations 259 12.3.1. Documentary survey 259 12.3.2. Geophysical investigations 260 12.3.2.1. Objectives 260 12.3.2.2. Advantage of various methods 260 12.3.2.3. General recommendations 263 12.3.3. Drilling and in situ geotechnical tests 264 12.3.3.1. Test drilling objectives 264 12.3.3.2. Setting up investigations boreholes 264 12.3.3.3. Test drilling methods 265 12.3.3.4. Samples for laboratory tests 267 12.3.3.5. In situ tests 268 12.4. Contents of the geological-geotechnical dossier of a project 269 Chapter 13. Guidelines for the Choice of Drilling Rigs and Equipment 273 13.1. General information 273 13.2. Choice of drilling rigs according to their power 274 13.2.1. Mini drilling rigs 275 13.2.2. Medium drilling rigs 276 13.2.3. Maxi drilling rigs 276 13.2.4. Mega drilling rigs 277 13.3. Choice of drilling rigs according to their technical characteristics 277 13.3.1. Chassis 277 13.3.1.1. Base 277 13.3.1.2. Trailer 278 13.3.1.3. Track mounted chassis 278 13.3.1.4. Wheeled chassis 278 13.3.2. Transmission of forces 278 13.3.2.1. Chain driven 278 13.3.2.2. Rack and pinion 279 13.3.2.3. Hydraulic jacks 279 13.3.3. Power limits 279 13.4. Drilling rods 279 13.5. Tools 281 13.5.1. Wing cutters 281 13.5.2. Spiral compactor bells 282 13.5.3. Fluted reamers 282 13.5.4. Rock reamers 282 13.5.5. Barrel reamers 283 Chapter 14. Guidelines for a Project Design 285 14.1. Basic principles of a pilot pattern 285 14.1.1. Rack angle and exit angle 285 14.1.2. First and last part of the drilling 286 14.1.3. Radius of curvature 286 14.1.3.1. Radius of curvature of the pilot hole 287 14.1.3.2. Combined radii 288 14.1.4. Roofing 288 14.1.5. Relation between the diameters of the pipeline and the borehole 289 14.2. Drilling plans 289 14.2.1. Longitudinal profile 289 14.2.2. Plan view 290 14.2.3. Cross-sections 290 14.2.4. Work site installation plans 291 14.2.5. Catenary and launching ramp 291 14.3. Design notes 291 14.3.1. Calculation for the work stage 292 14.3.1.1. Pulling forces at the level of the drilling head 292 14.3.1.2. Tractive forces at the level of the drilling machine 292 14.3.1.3. Calculation methods of pulling forces 293 14.3.1.4. Calculation of the drilling machine dimensions 293 14.3.1.5. Supports 293 14.3.1.6. Stresses suffered by the tubes 294 14.3.1.7. Protection against collapse 294 14.3.2. Calculation of operations stage 294 14.4. Work planning 294 14.5. Drilling fluids 295 14.5.1. General information 295 14.5.2. Selection criteria 297 14.5.3. Products used 298 14.5.4. Recycling and processing 299 14.5.5. Implementation at the site 301 14.5.6. Sludge treatment: technical and regulatory aspects 301 14.5.6.1. General considerations 301 14.5.6.2. Drilling wastes eliminations solutions 303 14.5.6.3. Development prospects 306 Chapter 15. Guidelines for the Management of the Site 307 15.1. Guidelines on lubrication, drilling fluids 307 15.1.1. General information 307 15.1.2. Selection criteria 308 15.1.3. Products used 308 15.1.4. Implementation at the site 308 15.1.5. Polluted sites, environment, slurry 308 15.2. Recommendations on reaming 309 15.2.1. Reaming diameter 309 15.2.2. Choice of the reamer 309 15.2.3. Multiple bores 310 15.2.4. Reaming sequences 310 15.2.5. Reaming speed 312 15.2.6. Installing a protective sleeve 313 15.3. Guidelines on safety and protection of environment 314 15.3.1. Safety at the work station (at the site) 314 15.3.1.1. Work on inclines 314 15.3.1.2. Work on rotating mechanical parts and tools 314 15.3.1.3. Risk of slipping increased by the presence of drilling mud 314 15.3.1.4. Respiratory risks related to the inhalation of bentonite powder 315 15.3.1.5. Handling of loads during lifting (drilling rod, reamers, etc.) 315 15.3.1.6. Significant torsional moments during the tightening or loosening of drilling rod/tool unions 315 15.3.1.7. Communication between the control cab, the drilling rig and the pipeline side 315 15.3.1.8. Work under thoroughfares 315 15.3.1.9. Risks of aggressions on underground structures 315 15.3.2. Security of machines 316 15.3.3. Security of drilling tools 316 15.3.4. Protection of the environment 316 Appendix 1. Glossary of Symbols Used 319 Appendix 2. Glossary of Horizontal Drilling 323 Bibliography 333 Index 341

About the Author :
The International Society for Trenchless Technology or ISTT is an organization founded in 1986 to promote and advance Trenchless Technology. ISTT encourages the formation and affiliation of societies sharing its objectives world-wide. There are now more than 20 such Affiliated Societies in 6 continents. Each is entitled to nominate a Director on the ISTT Board. For efficient day-to-day running, an Executive Sub-Committee is empowered to act for the full Board.