Practical Guide to Rock Tunneling

Dean Brox

• Publisher: CRC Press
• Year: 2017
• ISBN:
  9781351808675
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

This Practical Guide to Rock Tunneling fills an important void in the literature for a practical guide to the design and construction of tunnels in rock.

Practical Guide to Rock Tunneling takes the reader through all the critical steps of the design and construction for rock tunnels starting from geotechnical site investigations through to construction supervision. The guide provides suggestions and recommendations for practitioners on special topics of laboratory testing, durability of rock and acceptance for unlined water conveyance tunnels, overstressing or deep and long tunnels, risk-based evaluation of excavation methods, contract strategies, and post-construction inspections. Key considerations and lessons learned from selected case projects are presented based on the author's extensive international experience of over 30 years and 1000 km of tunneling for civil, hydropower, and mining infrastructure, including some of the most recognized projects in the world to date.

Instead of revisiting all theory and concepts that can be found in other sources, this book contains the hard learned lessons from the author's experience in the field of Rock Tunneling, gathered over 30 years of service.

Chapter 1

Introduction

The majority of tunnels that are planned and constructed for various forms of infrastructure requirements around world are located in urban areas and are sited at shallow depths in soils or overburden above bedrock. An increasing number of tunnels are however now being planned, designed, and constructed around the world at greater depths within bedrock, particularly for hydropower and mining projects, but also to a lesser extent for civil infrastructure. Over the past decade several of these such tunnels have experienced some serious problems during construction due to limited understanding of the key challenges associated with their design, construction, and operation. Tunnels planned to be constructed in bedrock are associated with their own unique design requirements and challenges due to the commonly recognized high variability of the geological conditions, its behaviour, and its influence on the design, construction and operation of tunnels.

A unique difference between tunnels in rock versus most of those tunnels located in soils is the possibility to allow the rock to form as the final internal surfaces of the tunnel and be exposed and not be fully lined by shotcrete or concrete which commonly presents economic benefits for a project. The acceptability of partially unlined or non-lined tunnels in rock, especially those for water conveyance, represents one of greatest challenges for tunneling practitioners as getting it wrong either during construction, but more during operations, can have significant cost impacts associated with repairs and loss of service. Several tunnel projects have benefitted from allowing the tunnel to be partially unlined where the quality of the rock conditions has been fully evaluated and confirmed to be durable and therefore acceptable for the intended service of long term operations.

It is important for tunneling practitioners to recognize that the planning, design, construction and operations of tunnels is a global-experienced based profession. The purpose of publishing the “Practical Guide to Rock Tunneling” is to pass on some relevant global and practical experience and lessons learned to the next generation of global tunneling practitioners, educators, and decision makers involved with rock tunnel projects.

This “Practical Guide to Rock Tunneling” is intended as a practical road map for the tunneling practitioner for the design, construction, and operations of tunnels in rock. As a noted handbook it provides recommendations for good practice for the industry, and in some cases, guidelines that are considered to represent good industry practice, including lessons learned from past projects. It is not intended to provide an exhaustive account of detailed information on each sub-topic of rock tunneling that has already been published and rather offers key references that can be further searched if required by the reader. While this “Practical Guide to Rock Tunneling” focusses on tunnels in rock, many of the following subjects are applicable to other types of underground excavations including shafts, chambers, and caverns.

The “Practical Guide to Rock Tunneling” is aimed at undergraduate and post-graduate students, young professionals starting in the tunneling industry, as well as individuals who do not have an extensive background in tunneling but who are responsible to make decisions for planned tunnel projects. The “Practical Guide to Rock Tunneling” takes the reader through all the critical steps of the design and construction for rock tunnels starting from the execution stages of a tunnel project, geotechnical site investigations, rock characterization, design, evaluation of risks, construction considerations, and through to construction supervision and post-construction inspections for safe future operations. The “Practical Guide to Rock Tunneling” also presents suggestions and recommendations for tunneling practitioners on special topics of laboratory testing, durability of rock and acceptance for unlined water conveyance tunnels, overstressing or deep and long tunnels, risk-based evaluation of excavation methods, contract strategies, and post-construction inspections. Key considerations and lessons learned from selected case projects are presented based on the author’s extensive international experience of over 30 years and 1000 km of tunneling for civil, hydropower, and mining infrastructure, including some of the most recognized projects around the world to date.

Tunneling is a practice that will continue to evolve with the development of new procedures and codes, methods of analyses for design, and technologies that will allow for the construction of tunnels in the future using different approaches than in the past. Tunneling practitioners should take the opportunity to attend tunneling conferences and seminars as well as courses to increase their knowledge of all of the aspects of tunneling. Tunneling practitioners should also read and review journals, conference proceedings and notes from seminars and courses to keep up to date on current advances and developments in tunneling technology. Various websites including those of most journals now provide an incredible wealth of very useful information on new tunneling projects, as well as the status and progress of current projects, including challenges during construction, and solutions implemented. The following websites are available:

•    TunnelTalk

•    Tunnel Business Magazine

•    Tunneling Journal

•    Tunnels and Tunneling International

•    Tunnel Builder

•    Tunnel (German and English)

•    AFTES (French and English)

Finally, senior tunneling practitioners should make their best attempts to devote some of their time for the mentoring of young tunneling practitioners in order to transfer valuable experience from past projects to the next generation of tunneling practitioners.

Chapter 2

Functional uses of rock tunnels

2.1 General

Tunnels in rock are being planned, designed and constructed for an increasing variety of plausible and environmentally accepted solutions for infrastructure requirements around the world. As space on the surface becomes increasingly limited and congested, particularly in urban areas, the use of underground space with tunnels can be expected to be identified as a viable solution for the transport of people, materials for everyday living.

In addition, existing and dormant tunnels are increasing being evaluated for alternative uses in society to take advantage of their pre-existing status and the application of well proven renovation and rehabilitation techniques for their transformation.

2.2 Functional uses

Tunnels designed and constructed in rock have historically been used and continue to be used for a wide variety of common infrastructure requirements including the following:

•    Access;

•    Bicycle;

•    Conveyor;

•    Combined Sewage/Stormwater Overflow (CSO);

•    Drainage;

•    Drinking Water;

•    Exploration;

•    Hydropower;

•    Pedestrian;

•    Pipelines (oil and gas);

•    Rail (Light Transit and Heavy Freight);

•    Sewage;

•    Strategic storage (military);

•    Traffic;

•    Utilities (electrical cables, fibre optics);

•    Water Diversion;

•    Water Supply (Irrigation)

•    Wine caves/storage, and;

•    Ventilation.

Tunnels in rock have also been designed and constructed for very specialized purposes including nuclear particle physics research as at CERN (European Organization for Nuclear Research), Switzerland and Stanford University in the United States. Several tunnels in rock (and other types of excavations) have also been designed and constructed as part of ongoing research of the storage of nuclear waste. Many tunnels in rock have also been designed and constructed for multiple purposes including mine access and conveyor, access and ventilation/utilities, flood control and traffic such as the Stormwater Management and Road Tunnel (SMART) in Kuala Lumpur, Malaysia (SMART Tunnel), and hydropower generation and irrigation. Figure 2.1 illustrates a historical rail tunnel built in the early 1900s that has been converted into a walking trail within a nature reserve in western Canada.

Figure  2.1   Historical rail tunnel.

A recent resurgence in the demand for energy and in particular renewable energy has resulted in the design and construction of several hydropower tunnels around the world. In addition, many urban areas continue to face transportation and stormwater control challenges and therefore an increasing amount of metro/subway and CSO tunnels are being built in many large cities. Furthermore, the use of underground space, and in particular, the conversion of historical and dormant tunnels is being recognized for new transportation solutions such as bicycle and pedestrian tunnels in many cities.

Chapter 3

Tunnel project execution

3.1 General

Tunnel projects are required to be executed in an appropriately planned sequence if they are expected to be successful and not associated with major delays. Clients and the developers of tunnel must recognize the importance of pre-planning and that key decisions are required to be made in order to allow key stages of a tunnel project to be advanced to the next stage. One of the first decisions required to be made is the method of delivery, that is, the procurement approach for the project. A project execution plan including a total project schedule is recommended to be prepared by the developer or client upon conceptual realization for a new rock tunnel to address all of the key requirements for a successful completion.

3.2 Project delivery method

Prior to the start of a tunnel project the client is required to select the method of project delivery for the project. The main two types or methods of project delivery are:

• Design-Bid-Build, and;

• Design-Build.

Design-bid-build (DBB) is the traditional method of project delivery whereby the client typically engages a tunnel consultant to prepare a final design that is bid upon by pre-qualified tunnel constructors and is awarded to a preferred tunnel constructor based on some form of evaluation criteria. The DBB approach generally require a longer total period of time for the completion of the project but has the advantage of the complete control of the design requirements by the client through each stage of design and construction. The DBB approach should be adopted as the project delivery method for all hydraulic tunnels owing to the typical complexity of the design associated with hydraulic tunnels and their associated works.

Design-build is essentially a fast-track approach of project delivery that typically requires a shorter period of time for project completion whereby the tunnel consultant engaged by the client only prepares a reference design in conjunction with a design criteria of the functional requirements which does not represent a final or detailed design. The reference design is then bid upon by pre-qualified DB teams comprising tunnel constructors and their designated designers and is awarded to a DB team based on evaluation criteria commonly including best price and best schedule. The DB approach has the advantage of attracting innovation into the design process by the DB team but the disadvantage of limited control over the final design and construction. The DB approach has been successfully used for several types of tunnel projects. The DB approach is not considered to be ideal for complex projects where the final design de...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Foreword
• About the author
• Acknowledgements
• Dedication
• Disclaimer
• List of figures and tables
• 1. Introduction
• 2. Functional uses of rock tunnels
• 3. Tunnel project execution
• 4. Site investigations
• 5. Rock characterization
• 6. Rock tunnel design
• 7. Tunnel stability
• 8. Tunnel excavation
• 9. Tunnel support
• 10. Tunnel lining requirements
• 11. Construction considerations
• 12. Construction risks and mitigation measures
• 13. Construction cost estimation for rock tunnels
• 14. Construction scheduling for rock tunnels
• 15. Tunnel contract strategy and implementation
• 16. Risk management
• 17. Inspection of rock tunnels
• 18. Renovation, repairs, and decommissioning
• 19. Case histories and lessons learned
• 20. Engagement and roles and responsibilities of professionals
• 21. Health and safety
• References