THE CHANNEL TUNNELGeological Problems Encountered and Solutions

Implemented

Introduction Geology Problems Summary

Overview

Contents of Presentation Description Geology Conditions Encountered Solutions End Result

Description of tunnel Cost Length Duration of Construction

Location

Introduction

Introduction Geology Problems Summary

Site Investigation

Boreholes

Probing

Seismic Surveys

Geology

Introduction Geology Problems Summary

Geology

Description of Geology Upper Chalk (Coniacian layer) Middle Chalk (Turonian layer) Lower Chalk (Cenomanian layer) Gault Clay (Albian layer)

Location of planned excavation Depth and layer Favourable properties

Geology

Introduction Geology Problems Summary

GeologyGeology

Introduction Geology Problems Summary

Detailed Solutions

Combination of measures implemented

TBM design resists 11 bar pressure Flexible hood controls

broken ground

Tunnel Lining Spheroidal graphite cast-

iron lining (SGI)

Problems

Introduction Geology Problems Summary

Detailed Solutions

Ground treatment Grouting from MST Tube a Machete forces

grout into rock Reduces permeability Eliminates water-bearing

fissures

Problems

Introduction Geology Problems Summary

Summary

Boring & probing establishes potential hazards

Chalk marl strata ideal

Solutions in unfavourable conditions

Importance of geology in civil engineering

Thank you for listening - Any questions?

Summary