Safe Tunnellling - A Management Process
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The document outlines the process for designing and constructing a tunnel project including: 1) Conducting site investigations and developing a geological and geotechnical model to design protection works for buildings and assess tunnel alignment and operational parameters. 2) Monitoring tunnel construction including TBM parameters, instrumentation readings, and building surveys to confirm geological profiles and ensure controlled settlement. 3) Implementing safe tunneling practices with minimal infrastructure impact including controlled settlement through optimized TBM face pressures and grout volumes.
Safe Tunnellling - A Management Process
- 1. IDENTIFY & DESIGN PROTECTION WORKS GEOLOGICAL -GEOTECHNICAL MODEL SITE INVESTIGATIONS (All previous data, desk study, other project data.) BUILDING RISK ASSESSMENTS & PROTECTION PLANS. Allowable Limits of Deformation ALIGNMENT OF RAIL TRACK & STATION LOCATION INSTRUMENTATION DESIGN SETTLEMENT ANALYSIS Ground loss, shield loss, tailskin loss, sensitivity TBM OPERATIONAL PARAMETERS & RANGE -Face Pressure, grout pressure/volume SURVEYS FOR UTILITIES, ID NATURE OF MATERIAL & ALLOWABLE LIMITS OF GEOLOGICAL PROFILE & GEOTECHNICAL PARAMETERS SITE INVESTIGATIONS Supplementary & Instrumentation Installation BUILDING CONDITION SURVEYS, STRUCTURAL SURVEYS, Confirm Extent and magnitude of settlement, correctness of face pressure Confirm /Reassess Geological profile and face pressures required to ensure settlements controlled. Confirm or Revise Building protection Works as required. Revise risk assessment MONITORING TBM Parameters Face Pressure Grout Volume & Pressure Muck Volume Thrust, torque & Advance Speed Instrumentation Drilling Data against geological profile Planned against actual settlement Monitoring of Treated Areas Immediate Actions Reading Frequency Accuracy checks Visual Inspections of surface/buildings SAFE TUNNELLING Controlled settlement, minimal impact on infrastructure, optimised face pressures, controlled progress CONSTRUCTION Tunnelling TBM Operation Face pressure, Grouting Volume & Pressure Muck Volume Thrust Torque Speed of Advance Steering / Survey Control Lining Erection Build Quality / Repars Alignment Ground Treatment Drilling Grouting Verification Immediate Actions Alarm Plans Standard Operating Procedures Emergency Plans DESIGN OF TUNNEL ADVANCE Horizontal & Vertical Alignment - deeper tunnels have greater pressures, tight curves may require tapered rings Geotechnical Interpretation - possible geological hazards, mixed face conditions, geological boundaries Face Pressures - control of face pressure to avoid stress relaxation & overexcavation Weights / Volumes - assessment of weight based on range of in-situ density, assess likely use of soil conditioning Instrument Plan - types & distribution of instruments based on predicted settlements and location of buildings, frequency of reading Settlement Contours & Settlement Limits - assessment of extent of predicted settlement, allows a check to be carried out during construction Required Consolidation Works - building protection worked to prevent any adverse effects due to settlement. High Risk Areas, Structures & utilities- indicated on drawings to advise of additional care/reporting Anticipated Anomalies & Actions - Loss of face pressure, additional grout, overexcavation Probing - predicted geology, tates of penetration TUNNEL MANAGEMENT PROCESS DESIGN INPUT DESIGN PROCESS DESIGN OUTPUT CONSTRUCTION INPUT CONSTRUCTION PROCESS CONSTRUCTION OUTPUT Input 'field data' &/or correction factors into design TBM - GROUND INTERACTION Compliance with settlement limits Compliance with Face Pressure & Grout requirements Compliance with alignment TBM Design Segment Design ALIGNMENT VALIDATION - Wriggle survey ALIGNMENT VERIFICATION - Track Work Validation CONFIRM ALIGNMENT - Design modifiaction may be necessary, signalling, route restrictions.