同济大学：《地下工程》课程电子教案（讲稿）04 Designs in Underground Engineering

CONTENTS 1.Introduction 2.Design Models for Underground Structures 3.Geotechnical Investigations 4.Instrumentation design 5.Feedback Analysis 百年同濟2 TONGILUNIVERSITY

2 1. Introduction 2. Design Models for Underground Structures 3. Geotechnical Investigations 4. Instrumentation design 5. Feedback Analysis CONTENTS

1.Introduction 1.1 Feature of Underground Engineering Theoretical Analysis Design of underground structure (different from above- ground structures,for the Experiences complicated geological conditions and interactions in structure-ground system) In-situ Measurement 百年同海3 TONGII UNIVERSITY

3 Design of an underground structure (different from above-ground structures, for the complicated geological conditions and interactions in structure-ground system) 1. Introduction 1.1 Feature of Underground Engineering Design of underground structure (different from above￾ground structures, for the complicated geological conditions and interactions in structure-ground system) Theoretical Analysis Experiences In-situ Measurement

1.Introduction 1.2 Design procedure Geology Investigation Lab and In-Situ Tests Geotechnical Properties ↓ Designer Experience Excavation Method and Support System Structural Model and Design Predictions No 0k? Yes Construction 反年日源4 TONGILUNIVERSITY

4 Geology Lab and In-Situ Tests Designer Experience Investigation Geotechnical Properties Excavation Method and Support System Structural Model and Design Predictions Ok? Construction Yes No 1. Introduction 1.2 Design procedure

1.Introduction 1.3 Design Principle Principle 1 The ground constitutes the main structural element of a tunnel Principle 1.1 Minimise disturbance to the ground during excavation or even increase its strength Principle 1.2 Allow displacements to mobilise its support capacity,leading to the ring effect Principle 1.3 Prevent excessive displacements to avoid loosening and consequently strength loss 百年同濟5 TONGII UNIVERSITY

5 1.3 Design Principle Principle 1 The ground constitutes the main structural element of a tunnel Principle 1.1 Minimise disturbance to the ground during excavation or even increase its strength Principle 1.2 Allow displacements to mobilise its support capacity, leading to the ring effect Principle 1.3 Prevent excessive displacements to avoid loosening and consequently strength loss 1. Introduction

1.Introduction 1.3 Design Principle Principle 2 Selection of an optimum support system,including support type, installation procedure and time,strength and stiffness Principle 2.1 Ring closure needed for support mobilisation Principle 2.2 Intimate contact between ground and support Principle 2.3 Inner support ring has to behave as a thin-walled shell,maximising normal stresses and minimising moments(avoiding internal shear) Principle 2.4 Support capacity increasing has to be done by reinforcement(steel sets,anchors etc.)rather than by cross-section thickening 百年同 *6

6 Principle 2 Selection of an optimum support system, including support type, installation procedure and time, strength and stiffness Principle 2.1 Ring closure needed for support mobilisation Principle 2.2 Intimate contact between ground and support Principle 2.3 Inner support ring has to behave as a thin-walled shell, maximising normal stresses and minimising moments (avoiding internal shear) Principle 2.4 Support capacity increasing has to be done by reinforcement (steel sets, anchors etc.) rather than by cross-section thickening 1. Introduction 1.3 Design Principle

1.Introduction 1.3 Design Principle Principle 3 Instrumentation of pilot excavations and main tunnel for displacements,loads and stresses Principle 3.1 Evaluate the stand-up time Principle 3.2 Select the most appropriate excavation method,support type and installation time Principle 3.3 Design the final tunnel support Monitoring of the tunnel behaviour Evaluate safety of the final structure 百年同濟7

7 Principle 3 Instrumentation of pilot excavations and main tunnel for displacements, loads and stresses Principle 3.1 Evaluate the stand-up time Principle 3.2 Select the most appropriate excavation method, support type and installation time Principle 3.3 Design the final tunnel support Monitoring of the tunnel behaviour Evaluate safety of the final structure 1. Introduction 1.3 Design Principle

1.Introduction 1.3 Design Principle Geology Uncertainty Concrete samples ■Every20to50m3 Test about 0.1 percent -See 100 percent out of the truck -Tunnels (samples 100 m) -About 0.0005 percent 百年同海8

8 Geology Uncertainty  Concrete samples  Every 20 to 50 m3  Test about 0.1 percent  See 100 percent out of the truck  Tunnels (samples @ 100 m) About 0.0005 percent 1. Introduction 1.3 Design Principle

1.Introduction 1.3 Design Principle Stress-Strain Analysis Closed-Form Solutions oSimple Geometry Homogeneous and Isotropic Media Linear Elastic Behaviour 」Numerical Methods Boundary Element oFinite Element ODiscrete Element 百年同海9

9 Stress-Strain Analysis  Closed-Form Solutions Simple Geometry Homogeneous and Isotropic Media Linear Elastic Behaviour  Numerical Methods Boundary Element Finite Element Discrete Element 1. Introduction 1.3 Design Principle

1.Introduction 1.4 Design Documents Geo-mechanical model Structural model of the tunnel Assumptions,completeness and type of calculations and simulations Monitoring threshold values Design Reviewer 百年同海10 TONGILUNIVERSITY

10 1.4 Design Documents  Geo- mechanical model  Structural model of the tunnel  Assumptions, completeness and type of calculations and simulations  Monitoring  threshold values  Design Reviewer 1. Introduction

2.Design Models for Underground Structures 2.1 Introduction Different kinds of model theories have been established to simulate different surrounding grounds. Category Main ideas and applications Empirical model Depend on experiences from past practice in the familiar engineering conditions. Action from ground is reflected as loads Load structure on structures,while the resistance from the Layer should be considered. Ground structure Structures and ground are modeled as a system model and numerical method is often involved. Convergence and The characteristic curves of ground and support confinement model should be used and this method is effective in the design of underground opening in soft rocks 百年同濟11 TONGIUNIVERSΠTY

11 2.1 Introduction Different kinds of model theories have been established to simulate different surrounding grounds. Category Empirical model Load structure Ground structure model Convergence and confinement model Main ideas and applications Depend on experiences from past practice in the familiar engineering conditions. Action from ground is reflected as loads on structures, while the resistance from the Layer should be considered. Structures and ground are modeled as a system and numerical method is often involved. The characteristic curves of ground and support should be used and this method is effective in the design of underground opening in soft rocks. 2. Design Models for Underground Structures