Slope Stability Analysis and Stabilization: New Methods and Insight

A number of methods currently exist for the analysis and design of slopes. This book provides a critical review of these and offers several more appropriate approaches for overcoming numerical convergence and the location of critical failure surfaces in two-dimensional and three-dimensional cases. New concepts in three-dimensional stability analysis, finite element analysis and the extension of slope stability problems to lateral earth pressure problems are also addressed. It gives helpful practical advice and design resources in the form of recommendations for good analysis and design practice, design charts and tables for the engineer.

Limitations are detailed of both limit equilibrium and the finite element method in the assessment of the stability of a slope, and guidance is provided for assessing the fundamental assumptions and limitations of stability analysis methods and computer modelling. The book provides ample examples to illustrate how this range of problems should be dealt with. The final chapter touches on design and its implementation on site. The emphasis is on the transfer of the design to its physical implementation on site in a holistic way, taking full account of the latest developments in construction technology.

Engineering and construction problems tend to be pigeonholed into different classes of problem such as slope stability, bearing capacity and earth pressure behind retaining structures. This is quite unnecessary. This book offers a unified approach, which is conceptually, practically and philosophically more satisfying.

Y.M. Cheng is Associate Professor at Hong Kong Polytechnic University.

C.K. Lau is the Managing Director of Fong On Geotechnics Limited. He is the Founder Chairman of AGS (HK) and a Past Chairman of HKIE Geotechnical Division.

Chapter 1 Introduction 1-25
1.1 Introduction
1.2 Background
1.3 Closed-form Solutions
1.4 Engineering Judgment
1.5 Ground model
1.6 The Status Quo
1.7 Ground Investigation
1.8 Design Parameters
1.9 Groundwater Regime
1.10 Design Methodology
1.11 Case Histories


Chapter 2 Slope stability analysis method 26-90
2.1 Introduction
2.1.1 Types of stability analysis
2.1.2 Definition of the Factor of Safety
2.2 Slope stability analysis – limit equilibrium method
2.2.1 Limit equilibrium formulation of slope stability analysis methods
2.2.2 Interslice force function
2.2.3 Reduction to various methods ad discussion
2.2.4 Solution of nonlinear factor of safety equation
2.2.5 Examples on slope stability analysis
2.3 Miscellaneous Consideration on Slope Stability Analysis
2.3.1 Acceptability of the failure surfaces and results of analysis
2.3.2 Tension crack
2.3.3 Earthquake
2.3.4 Water
2.3.5 Saturated density of soil
2.3.6 Moment point
2.3.7 Use of soil nail/reinforcement
2.3.8 Failure to converge
2.3.9 Location of the critical failure surface
2.3.10 3D analysis
2.4 Limit analysis
2.4.1 Lower Bound Approach
2.4.2 Upper Bound Approach
2.5 Rigid element
2.5.1 Displacements of the Rigid Elements
2.5.2 Contact Stresses Between Rigid Elements
2.5.3 Principle of Virtual Work
2.5.4 Governing Equations
2.5.5 General procedure of REM computation
2.6 Relation between the REM and the slice based approach
2.7 Design figures and tables
2.8 Method based on Variational principle or extremum principle
2.9 Upper and lower bounds to factor of safety and f(x) by lower bound method
2.10 Finite element method
2.11 Distinct element method

Chapter 3 Location of critical failure surface, convergence and other problems 91-140
3.1 Difficulties in locating the critical failure surface
3.2 Generation of trial failure surface
3.3 Global optimization methods
3.3.1 Simulated annealing algorithm (SA)
3.3.2 Genetic algorithms (GA)
3.3.3 Particle swarm optimization algorithm (PSO)
3.3.4 Simple harmony search algorithm (SHM)
3.3.5 Modified harmony search algorithm (MHM)
3.3.6 Tabu search algorithm
3.3.7 Ant colony algorithm
3.4 Verification of the global minimization algorithm
3.5 Presence of Dirac Function
3.6 Numerical studies of the efficiency and effectiveness of various optimization algorithms
3.7 Sensitivity of the global optimization parameters on the performance of the global optimization method
3.8 Convexity of critical failure surface
3.9 Lateral earth pressure determination
3.10 Convergence
3.10.1 Parametric Study on Convergence
3.10.2 Combined Impact of Optimization and Double QR analysis
3.10.3 Reasons for Failure to Converge
3.11 Importance of the methods of analysis



Chapter 4 Discussion on limit equilibrium and finite element methods for slope stability analysis 141-185



Comparisons of SRM and LEM


Stability analysis for a simple and homogeneous soil slope using LEM and SRM


Stability analysis of a slope with a soft band


Local minimum in LEM


Discussion and Conclusion


Chapter 5 Three-dimensional slope stability analysis 186-225
5.1 Limitation of classical limit equilibrium methods – sliding direction, transverse load
5.2.1 New formulation for 3D slope stability analysis – Bishop, Janbu simplified, Morgenstern-Price by Cheng
5.2.2 Reduction to 3D Bishop and Janbu simplified method
5.2.3 Numerical implementation of Bishop, Janbu and Morgenstern-Price methods
5.2.4 Numerical Examples and Verification
5.2.5 Comparison between Huang’s method and the present methods for transverse earthquake load
5.2.6 Relation with classical 3D analysis methods
5.2.7 Problem of cross section force/moment equilibrium for Morgenstern-Price method
5.2.8 Discussion on l xy for Morgenstern-Price analysis
5.2.9 Discussion on 3D stability formulation
5.3 3D Limit analysis
5.4 Location of general critical non-spherical 3D failure surface
5.4.1 3D NURBS surfaces
5.4.2 Spherical and Ellipsoidal surface
5.4.3 Selection of sliding surfaces
5.4.4 Optimization Analysis of NURBS surface
5.5 Case Studies in Three-dimensional Limit Equilibrium Global Optimization Analysis
5.6 Effect of curvature on factor of safety

Chapter 6 Implementation



Introduction


FRP nail


Drainage


Appendix

References