This book presents the theoretical bases and the application tools for using the 'convergence-confinement' method which is a rational method largely used in design engineering for tunneling. Until recently, the stability conditions of underground works and the choice of support methods were essentially defined on the basis of good practice or empirical methods. The progress made, on one hand on the knowledge of the constitutive laws of soils and rocks and, on the other hand on the numerical modeling of the interaction between the ground and the structures have led to the development of robust design tools for tunnels supports. The convergence-confinement method makes it possible to simulate the excavation of a tunnel and the installation of the support using a simple plane strain model. The book presents the theoretical bases of the method and its most recent developments. Closed-form solutions for stress and displacement fields around tunnels are provided for elastic, viscoelastic and elasto-plastic behavior of the ground. More generally, the principles for applying the method in numerical models are presented.
Author(s): Marc Panet, Jean Sulem
Series: Springer Tracts in Civil Engineering
Publisher: Springer
Year: 2022
Language: English
Pages: 161
City: Cham
Foreword
Contents
1 Introduction
1.1 Construction Methods
1.1.1 Conventional Construction Methods
1.1.2 Tunnel Boring Machines (TBM)
1.2 Displacements Induced by Tunnel Construction
1.2.1 Tunnel Convergence
1.2.2 Pre-convergence and Extrusion
1.3 Ground Instabilities and Failures in Underground Works
1.4 Support Functions
1.5 Time-Dependent Deformation
1.6 Natural State of Stress
1.7 Choice Tunnel Support and Lining
1.7.1 Geotechnical Classifications for Tunnels
1.7.2 Design Methods Based on the Analysis of the Ground Support Interaction
1.8 Principles of the Convergence-Confinement Method
Appendix: Rock Mass Classifications
AFTES Classification
Rock Mass Rating
Q Quality Index
Ground Strength Index (GSI)
References
2 Methods of Support
2.1 Unsupported Distance
2.2 Normal Stiffness and Bending Stiffness of a Support
2.3 Normal Stiffness and Bending Stiffness of a Circular Cylindrical Shell
2.4 Timber Supports
2.5 Steel Ribs
2.6 Bolting
2.7 Shotcrete
2.8 Rings of Prefabricated Segments
2.9 Yielding Elements
2.10 Composite Supports
2.11 Two-Phase Supports
2.12 Support of the Face
2.12.1 Support of the Face by Bolts and Shotcrete
2.12.2 Ground Treatments Ahead of the Face
2.12.3 Confinement of the Tunnel Face
2.13 Presupport
2.14 Lining
References
3 The Convergence-Confinement Method for a Tunnel Driven in an Elastic Medium
3.1 Displacements Field and Convergence of an Unsupported Tunnel
3.2 Stress and Displacement Fields Around an Unsupported Tunnel
3.2.1 Tunnel with Circular Cross Section Excavated in an Elastic Medium Under Isotropic Initial Stress State
3.2.2 Tunnel with Circular Cross Section Excavated in an Elastic Medium Under Anisotropic Initial Stress State
3.3 Application of the Convergence-Confinement Method
3.3.1 Isotropic Initial Stress State
3.3.2 Anisotropic Initial Stress State
Appendix 1: Complex Variable Method for Solving Two-Dimensional Elasticity Problems
Appendix 2: Stress and Displacement Fields Around a Tunnel with Circular Cross Section Excavated in an Elastic Medium with Transverse Isotropy
References
4 The Convergence-Confinement Method for a Tunnel Driven in an Elasto-Plastic Medium
4.1 Usual Plasticity Models
4.1.1 Tresca Yield Criterion
4.1.2 Mohr–Coulomb Yield Criterion
4.1.3 Hoek and Brown Yield Criterion
4.1.4 Other Usual Plasticity Criteria
4.2 Development of a Plastic Zone
4.2.1 Deconfinement Ratio at the Onset of Plasticity
4.2.2 Stability Number
4.3 Stress and Displacement Fields for an Elastic Perfectly Plastic Behavior of the Ground
4.3.1 Tresca Yield Criterion
4.3.2 Mohr–Coulomb Yield Criterion
4.3.3 Hoek and Brown Yield Criterion
4.4 Brittle Failure
4.5 Effect of Gravity on the Stability of the Vault of the Tunnel
Appendix: Tunnel with Circular Section Excavated in an Elastic Perfectly Plastic Medium with Mohr–Coulomb Yield Criterion. Axi-symmetric Case—Face Mode and Edge Mode
References
5 Longitudinal Displacement Profile
5.1 Longitudinal Displacement Profile for an Unsupported Tunnel
5.2 Longitudinal Displacement Profile for a Supported Tunnel
5.2.1 Method of Bernaud and Rousset
5.2.2 Method of Nguyen-Minh and Guo
5.2.3 Comparison of the Accuracy of the Implicit Methods and of the Empirical Expressions
5.3 Taking into Account of a Pre-support or a Confining Pressure on the Face
5.3.1 Taking into Account of a Pre-support
5.3.2 Evaluation of the Deconfinement Ratio for TBM Excavation with a Pressurized Shield
References
6 The Convergence-Confinement Method and the Time-Dependent Behavior of the Rock Mass
6.1 Analysis of Convergence Measurements
6.2 Excavation of Tunnel with a Circular Section in a Viscoelastic Rock Mass
6.3 Excavation of Tunnel with a Circular Section in a Visco-Elastic–plastic Rock Mass
6.4 Viscoplastic Models
6.5 Taking into Account the Hydraulic Regime
6.5.1 Ground Reaction Curve for a Poroelastic Medium
6.5.2 Application of the Convergence-Confinement Method for a Poroelastic Saturated Medium
6.5.3 Time to Establish the Steady-State Hydraulic Regime
6.5.4 Excavation in a Saturated Poroplastic Medium
References
7 Use of Numerical Models
7.1 Background
7.2 Numerical Modeling of Conventional Tunneling
7.3 Numerical Modeling of TBM Tunneling
7.4 2D Numerical Modeling for the Application of the Convergence-Confinement Method
7.4.1 Principles of the Numerical Simulation
7.4.2 Example
7.5 Example of 3D Numerical Simulation
References
