The Observational Method in Civil Engineering: Minimising Risk, Maximising Economy

Cover
Half Title
Title Page
Copyright Page
Table of Contents
Foreword
Authors
Glossary
Abbreviations
Notation
Introduction
1. The Art of Achieving Agreement
1.1 Key Factors
1.2 The Power of Progressive Modification
1.3 Summaries of Featured Case Histories
1.3.1 The Channel Tunnel (1988–1991)
1.3.2 The Mansion House (1989–1991)
1.3.3 Limehouse Link (1991–1993)
1.3.4 Heathrow Express Cofferdam (1994–1995)
1.3.5 Heathrow Airport Multi-Storey Car Park (1995–1996)
1.3.6 Boston Central Artery (1991–2001)
1.3.7 Irlam Railway Bridge Embankment (1997–1999)
1.3.8 Heathrow Airport Airside Road Tunnel (ART)
(2001–2003)
1.3.9 Wembley Stadium Arch (2004–2005)
1.3.10 Crossrail Blomfield Box (2012–2014)
1.3.11 Crossrail Moorgate Shaft (2014–2015)
1.3.12 Heathrow Airport Terminal 5 Tunnels (2005–2006)
References
2. Channel Tunnel Cut and Cover Works (1988–1990)
2.1 Introduction
2.2 Key Aspects of Design and Construction
2.2.1 Overview
2.2.2 Geology
2.2.3 Design Uncertainties
2.3 Achieving Agreement to Use the OM
2.3.1 Creating Opportunity
2.3.2 Finding the Key
2.4 Implementation of the OM
2.4.1 Development of Progressive Modification
2.4.2 Construction Sequence, Form and Geometry
2.4.3 Design Constraints
2.4.4 Addressing Uncertainty
2.4.5 Instrumentation and Monitoring
2.4.6 Castle Hill East – The OM Stage 1: Initiation
2.4.7 Measured Performance at CHE
2.4.8 Sugarloaf Hill – The OM Phase 2: Development
2.4.9 Castle Hill West – The OM Phase 3: Conclusion
2.4.10 Landslip Loading
2.5 Connection with the NATM Tunnels
2.5.1 Interface Coordination
2.5.2 The OM and ‘Most Probable’ Conditions
2.6 Conclusions
References
3. Mansion House (1989–1991)
3.1 Introduction
3.2 Key Aspects of the Design and Construction
3.2.1 Foundations in the Building’s History
3.2.2 The Challenge Presented by the DLR
3.3 Achieving Agreement to Use the OM
3.3.1 Addressing Complexity
3.3.2 Creating the Solution through the OM
3.3.3 Introduction of the OM Traffic Light System
3.4 Implementation of the OM
3.4.1 Managing Risk
3.4.2 The Profound Influence of Soil/Structure Interaction
3.4.3 Instrumentation and Monitoring
3.4.4 Temperature-Induced Cyclic Movements
3.4.5 Development of Progressive Modification
3.4.6 Critical Observations, Trigger Levels and Contingencies
3.5 Results
3.5.1 Overview
3.5.2 Detailed Assessment
3.5.3 The Benefit of Hindsight
3.6 Conclusions
References
4. Limehouse Link (1991–1993)
4.1 Introduction
4.2 Key Aspects of Design and Construction
4.2.1 Overview
4.2.2 Geology
4.2.3 Original Design
4.2.4 Value Engineering
4.3 Achieving Agreement to Use the OM
4.3.1 Overcoming Traditional Barriers
4.3.2 The Key to Consensus
4.4 Implementation of the OM
4.4.1 Extending the Process of Progressive Modification
4.4.2 Sequence for Each Implementation of the OM
4.4.3 Observations, Trigger Levels and Contingencies
4.4.4 Measured Performance
4.4.5 Increasing Beneficial Design Changes
4.4.6 Personnel and Communication
4.4.7 Achieving Simple and Effective Monitoring
4.4.8 Construction Plant and Resources
4.5 Limehouse Basin Construction
4.5.1 Reaching the Practical Limits of the OM
4.5.2 Monitoring Becomes Intensive
4.5.3 Implementation of the OM in Limehouse Basin
4.5.4 Added Value Still Achieved
4.6 Risk and Insurance
4.7 Conclusions
References
5. Heathrow Express Cofferdam (1994–1995)
5.1 Introduction
5.2 Key Aspects of Design and Construction
5.2.1 Overview
5.2.2 Geology – Conditions Prior and Post Collapse
5.2.3 Contractual Conditions
5.2.4 The Cofferdam
5.3 Achieving Agreement to Use the OM
5.3.1 Safety and Innovation
5.3.2 Progressive Modification Offers the Way Forward
5.4 Implementation of the OM
5.4.1 The Recovery Solution
5.4.2 Cofferdam Configuration
5.4.3 Innovations in Piled Wall Design and Construction
5.4.4 Design Development
5.4.5 A Bespoke Design for Progressive Modification
5.4.6 Observations, Trigger Levels and Contingencies
5.4.7 Measured Performance and Design Improvements
5.5 Conclusions
References
6. Heathrow Airport Multi-Storey Car Park 1A (1995–1996)
6.1 Introduction
6.2 Key Aspects of Design and Construction
6.2.1 Overview
6.2.2 Geology
6.2.3 Tunnel Construction
6.2.4 Car Park Structure
6.3 Achieving Agreement to Use the OM
6.4 Implementation of the OM
6.4.1 Traffic Lights, Trigger Levels and Contingencies
6.4.2 Risk Assessments
6.4.3 Predicted Ground Movements
6.4.4 Measured Settlements
6.5 Effects on the Building and Remedial Measures
6.5.1 Damage Assessment
6.5.2 Remedial Measures
6.5.3 Structural Response: Actual vs Predicted
6.5.4 Background to the Risk Assessment
6.5.5 Evaluation of Actual Response
6.5.6 Key Lessons Learned
6.6 Conclusions
6.6.1 A Triple Irony
6.6.2 Beware the Oddball – Reflections on Peck (1998)
References
7. Boston Central Artery Tunnel Jacking (1991–2001)
7.1 Introduction
7.2 Key Aspects of Design and Construction
7.2.1 The Project
7.2.2 Geology
7.2.3 Original Design Concept
7.2.4 Innovations in Tunnel Jacking
7.3 Achieving Agreement to Use the OM
7.3.1 A Dramatic Simplicity
7.3.2 ‘A Rose by Any Other Name’
7.4 Implementation of the OM
7.4.1 The Primary Objective
7.4.2 Solving the Spatial Challenges
7.4.3 The Process for Tunnel Jacking
7.5 Construction Activities Causing Ground Movements
7.5.1 Installation of Diaphragm Walls Forming the Thrust Pits
7.5.2 Jet Grouting of the Low Level In-Situ Strut
7.5.3 Bulk Excavation of the Thrust Pits
7.5.4 Installation of Vertical Freeze Pipes
7.5.5 Heave and Lateral Movement of the Ground during Freezing
7.5.6 Ground Movements during Tunnelling Operations
7.5.7 Longer-Term Ground Movements during Thawing and Consolidation
7.6 Instrumentation and Monitoring
7.6.1 Railway Track Monitoring
7.6.2 Diaphragm Wall Monitoring
7.6.3 Ground Movement and Groundwater Monitoring
7.7 Managing Interfaces
7.7.1 Tunnel Launch Pads
7.7.2 Jet Grouting
7.7.3 Ground Freezing
7.8 Fostering a Collaborative Approach
7.8.1 Teamwork
7.8.2 Extending the Limits of Progressive Modification
7.9 Results
7.10 Conclusions
References
8. Irlam Railway Embankment (1996–1998)
8.1 Introduction
8.2 Key Aspects of Design and Construction
8.2.1 Overview
8.2.2 Geology
8.2.3 Bridge Assessment
8.2.4 Project Constraints
8.3 Evaluation of Embankment Options
8.3.1 Identifying Viable Options
8.3.2 Potential Adverse Effects on Bridge Foundations
8.4 Achieving Agreement to Use the OM
8.5 Implementation of the OM
8.5.1 Trigger Levels and Contingency Measures
8.5.2 Instrumentation and Monitoring
8.5.3 Pre-load Embankment Construction
8.5.4 Removal of Pre-Load and EPS Embankment Construction
8.6 Conclusions
References
9. Heathrow Airport Airside Road Tunnel
9.1 Introduction
9.2 Key Aspects of Design and Construction
9.2.1 Portal Structures and Tunnels
9.2.2 Geology
9.2.3 Base Case Design
9.2.4 Construction Sequence
9.2.5 Retaining Wall Design
9.3 Achieving Agreement to Use the OM
9.3.1 Promoting Innovation
9.3.2 Addressing the Issue of Precedent
9.4 Implementation of the OM
9.4.1 A Big Challenge at a Small Scale
9.4.2 The Breakthrough Concept
9.4.3 Instrumentation, Trigger Levels, Contingencies and Measured Performance
9.5 Innovation in Blinding Struts
9.5.1 Interface with the Piccadilly Line Tunnel
9.5.2 Implementing Innovation
9.6 Conclusions
References
10. Raising the 133 m High Triumphal Arch at the New Wembley Stadium (2002–2004)
10.1 Introduction
10.2 Key Aspects of Design and Construction
10.2.1 Overview
10.2.2 Foundations and Geotechnics
10.2.3 Arch Raising
10.3 Achieving Agreement to Implement the OM
10.3.1 Creating Opportunity
10.3.2 Assessment of Foundation Behaviour during Arch Raising
10.3.3 Preliminary Pile Load Tests
10.4 Establishing Trigger Levels and Contingency Measures
10.4.1 Foundation Analysis
10.4.2 Trigger Levels and Contingency Plans
10.5 Implementation of the OM
10.5.1 Initial Surveys
10.5.2 Observed Pile Group Deformation
10.6 Conclusions
References
11. Crossrail Blomfield Box (2012–2015)
11.1 Introduction
11.2 Key aspects of Design and Construction
11.2.1 Overview
11.2.2 Geology
11.3 Achieving Agreement to Use the OM
11.3.1 Potential Hazards
11.3.2 Design Conditions
11.4 Implementation of the OM
11.4.1 Dewatering Systems – Potential Failure Scenarios
11.4.2 Instrumentation and Monitoring
11.4.3 Traffic Light System for the OM
11.4.4 Dewatering System, Observations Outside of the Blomfield Box
11.4.5 Displacement of Contiguous Pile Retaining Wall
11.4.6 Dewatering System, Observations Inside the Blomfield Box
11.4.7 Dewatering System, Modifications during Final Phase of Excavation
11.4.8 Summary of Changes Introduced through Implementation of the OM
11.5 Conclusions
References
12. Crossrail Moorgate Shaft (2012–2014)
12.1 Introduction
12.2 Key Aspects of Design and Construction
12.2.1 Overview
12.2.2 Geology
12.3 Achieving Agreement to Use the OM
12.3.1 Design Objectives and Constraints
12.3.2 Creating Opportunity
12.3.3 Verification Process
12.4 Implementation of the OM
12.4.1 Key Steps and Activities
12.4.2 Verification Point 1
12.4.3 Verification Point 2
12.4.4 Verification Point 3
12.4.5 Summary of Changes Introduced through Implementation of the OM
12.4.6 Reflections on the Role of Analysis and Bayesian Updating
12.5 Conclusions
References
13. Reflections on the Advantages and Limitations of the Observational Method
13.1 The Legacy of Terzaghi and Peck
13.2 Advantages and Limitations of the OM
13.2.1 Lessons Learned from the Case Histories
13.2.2 The Importance of Simplicity
13.2.3 Key Limitations
13.2.4 Heathrow Terminal 5 Tunnels – An Illustrative Case
History
13.3 Progressive Modification – Solving the Issue of the ‘Most
Probable’
References
14. Some Observations on the Way Forward
14.1 The 1996 Overview
14.2 Commercial and Contractual Environment
14.2.1 Overview
14.2.2 Design and Build
14.2.3 Developing Greater Collaboration
14.2.4 Value Engineering Clauses
14.3 Instrumentation and Monitoring
14.3.1 General Considerations
14.3.2 Performance Limits and Traffic Lights
14.4 Progressive Modification – A Comprehensive Approach
14.5 Peer Review
14.6 Recommendations for OM Practitioners
References
Index