inspection, assessment

Transcription

1 CIRIA C671 London 2009 Tunnels: inspection, assessment and maintenance L McKibbins R Elmer K Roberts Mott MacDonald Ltd Golder Associates (UK) Ltd Atkins Classic House, Old Street, London EC1V 9BP TEL: +44 (0) FAX: +44 (0) enquiries@ciria.org WEBSITE:

2 Contents Summary Acknowledgments Boxes Figures Tables Glossary Abbreviations v xiv xiv xx xxll xx'x 1 Introduction and background Background Purpose and scope of work Application Issues dealt with in this guide How to use this guide 5 2 Construction and behaviour Tunnel construction History Construction method Cut-and-cover tunnels Bored tunnels Excavation methods Stress redistribution Ground failure mechanisms Temporary support Primary and secondary linings Construction shafts Shaft construction techniques Shaft eyes Closed shafts (blind shafts) Masonry linings Lining profile, thickness and quality Lining construction Inverts and drainage Brickwork bonds Construction joints in brickwork Masonry materials Mortar Stone Brick Structural behaviour of masonry 36 viii

3 2.4 Metal linings Cast iron Steel Pre-cast concrete linings Lining forms Bolted pre-cast concrete lining Expanded concrete linings Casting methods and reinforcement Tunnel performance Structural deterioration Materials deterioration Masonry linings Metal linings Deterioration of concrete linings Deterioration of unlined tunnel support Effect of fire on tunnels The influence of structural form Concrete and masonry linings Metallic linings Shaft performance Effect at ground level 61 3 Tunnel asset management The need for tunnel management 3.2 Special requirements 3.3 Loss of performance and its consequences Appraisal of current condition, performance and serviceability Maintenance strategies Planned maintenance Reactive maintenance Maintenance planning and prioritisation Assessment of tunnel criticality Effect ofmaintenance strategy on tunnel performance Effect of maintenance strategy on inspection intervals Optimising planned maintenance strategies Deferral of maintenance Minimising disruption from tunnel maintenance Tunnel management procedures and tools Tunnel information requirements Tunnel management systems Tunnel identification and referencing systems Managing risk Whole-life asset costs Health and safety and environmental management Health and safety management 78 CIRIA C671 Tunnels 2009 ix

4 3.6.2 Competence and training of staff Heritage conservation Environmental conservation Conservation bodies and environmental legislation Wildlife conservation Managing environmental impact Tunnel operational safety and fire risks Management of tunnel shafts Shaft identification and location Maintaining shafts Development of land above shafts Management of closed and disused tunnels 91 4 Condition appraisal Types and sources of information Desk studies and existing information Visual inspection Advantages and limitations of visual inspection Types of visual inspection and inspection intervals Competence of inspection staff Visual inspection procedures and techniques Optimising inspection procedures and results Tunnel investigation Objectives of tunnel investigation Investigation strategy and reliability of results Techniques for tunnel investigation Selection of investigation techniques Optimising tunnel investigations and results Tunnel monitoring Objectives of tunnel monitoring Monitoring instrumentation and techniques Selection and design of monitoring systems 4.6 Preparing for inspections and investigations Risk assessment Access, programming and timing Location and inspection of tunnel shafts Detection and location ofunknown hidden shafts Shaft inspection Interpretation of inspection and investigation data The importance of good interpretation Considerations for interpretation 4.9 Structural assessment of tunnels Assessment in 123 principle Qualitative assessment Analytical assessment 125 x

5 Cast iron and steel linings Multi-level assessment procedure Structural defects Reporting on and interpreting asset condition Reporting inspection and investigation results Initial evaluation and identification of sensitive structures Interpretation of results Condition ratings Selecting and carrying out works on tunnels and shafts Selection, planning and preparation for works Planning and programming Managing risk Selection of techniques Method statements and risk assessments Completion of works and beyond Tunnel repair measures, Routine (preventative) maintenance Tunnel cleaning Drainage maintenance Management and removal of vegetation Repointing of masonry-lined tunnels Application of protective coatings Metal tunnel linings Concrete, brick and masonry linings Remedial repairs Masonry linings Patch repairs Crack repairs Ring separation repair Metal tunnel linings Cast iron lining repairs Wrought iron and steel repairs Alternative repair solutions Concrete tunnel linings Concrete repairs Other types of treatment and repair Strengthening and structural improvement Replacement and strengthening existing tunnel linings Replacement of tunnel lining Tunnel strengthening Replacement of structural elements Underpinning of masonry-lined tunnels Continuous strip foundations Piling methods 186 CIRIA C671 Tunnels 2009 xi

6 5.5.3 Invert repair (strengthening/replacement) Rock stabilisation: unlined tunnels Treatment of tunnel shafts Access for working Shaft lining maintenance, repair and decommissioning Deteriorating cross-members Water ingress Shaft lining stability Relining Filling Grouting Capping Water Ingress and control General considerations Passive measures Drip trays (including guttering and down pipes) Secondary lining systems (or drainage membrane) Weep holes (and pipes) Channelling Active measures Caulking, bolt holes, grummets and grout holes Caulking joints in segmental linings Sealing bolt holes Sealing grout holes Surface sealing Grouting Grouting technique selection Cementitious grouts Chemical (resin) grouts Grouting masonry-lined tunnels Grouting procedures Metal or pre-cast concrete segmental lined tunnels Concrete-lined tunnels Void grouting behind linings Alternative measures Groundwater lowering (dewatering using well-points) Electro-osmosis (dewatering) Recommendations and future needs Recommendations for good practice Areas requiring further research and future needs 231 References 233 Further reading 246 Regulations and standards 247 xii

7 Regulations 247 Standards 247 Appendices Al Case studies 249 Case study 1 Remedial treatments to Folkestone Rail tunnels 250 Case study 2 Investigation and treatment of ground instability and water ingress at Blackheath tunnel 267 Case study 3 Strengthening of Brunei's Thames Tunnel 281 Case study 4 Standedge North Railway Tunnel: investigations and design of major remedial works 288 Case study 5 Geophysical surveying to identify hidden shafts 304 Case study 6 Relining of Blisworth Tunnel 306 Case study 7 Leak sealing and rehabilitation of Sewer Tunnels 310 Case study 8 Management of a disused and deteriorated rail tunnel 316 Case study 9 Reconstruction of an underground line tunnel at Old Street 321 Case study 10 Inspection and maintenance ofa raw water tunnel 328 Case study 11 Investigation and construction joint mapping of Haymarket Tunnels..335 Case study 12 Relining of Sugar Loaf Tunnel 338 Case study 13 Structural monitoring strategy for the Channel Tunnel 340 Case study 14 Invert reconstruction and other structural repairs to Netherton Canal Tunnel 346 Case study 15 Piling adjacent to deep and near-surface tunnels in London 350 Case study 16 Predicting and monitoring the effects of adjacent construction on masonry-lined tunnels 354 Case study 17 A feasibility-based risk matrix for option selection 359 Case study 18 Tunnel fires, collapses and other serious incidents 369 A2 Sources of existing information 385 A2.1 Sources of historical information 385 A2.2 Sources of geological and hydrogeological information 387 A2.3 Aerial photographs 389 A2.4 Utilities and services 389 A2.5 Walkover survey 389 A3 Visual inspection procedures and observations 393 A3.1 Preparation 393 A3.2 Observation and recording 393 A4 Inspection, Investigation and monitoring techniques 403 A4.1 Inspection, mapping and simple on-site tests 404 A4.2 Sampling and testing techniques 410 A4.3 Specialist non-destructive investigation techniques 419 A4.4 Techniques for monitoring 429 A5 Detection and location of hidden shafts 433 A5.1 Multi-phase approach to shaft location 433 A6 Investigation and assessment of unlined tunnels and shafts 442 A6.1 Desk study 442 CIRIAC671 Tunnels 2009 xiii

8 A6.2 Reconnaissance visit 442 A6.3 Detailed survey 442 A6.4 Scan line mapping 443 A6.5 Rock mass mapping 444 A6.6 Rock mass classification systems 445 A7 Guidance on structural assessment 447 A7.1 Limit state assessment 447 A7.2 Assessment principles 448 A7.3 Worked examples 452 Worked example Worked example 1: Cast iron 453 2: Concrete 461 Worked example 3: Masonry 469 xiv