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2020 | Buch

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Failure Mechanism and Stability Analysis of Rock Slope

New Insight and Methods

verfasst von: Assoc. Prof. Ke Zhang

Verlag: Springer Singapore

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

This book presents in-depth coverage of laboratory experiments, theories, modeling techniques, and practices for the analysis and design of rock slopes in complex geological settings. It addresses new concepts in connection with the kinematical element method, discontinuity kinematical element method, integrated karst cave stochastic model-limit equilibrium method, improved strength reduction method, and fracture mechanics method, taking into account the relevant geological features. The book is chiefly intended as a reference guide for geotechnical engineering and engineering geology professionals, and as a textbook for related graduate courses.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract

This chapter summarizes the literature review of past work on the crack coalescence processes in rocks and numerical methods of rock slope stability analysis. Two different failure mechanicsms are recognized, namely, large-scale, global failure and structually-controlled failure. The main contents in this book are introduced.

Ke Zhang

Experimental Studies on Shear Failure Mechanism of Rock Masses

Frontmatter

Chapter 2. Influence of Flaw Inclination on Shear Fracturing and Fractal Behavior

Abstract

This chapter investigates the influence of flaw inclination on the shear fracturing and fractal behavior of rock bridges in jointed rock slopes. Flaw geometry is a new combination of two edge-notched flaws and an imbedded flaw, which is different from those in the previous studies, where parallel or coplanar flaws are used. The physical implications of the shear-box test applied to result to rock slopes are studied. In all of the cases of the shear-box tests, the coalescence is produced by the linkage of shear cracks, and two types of coalescence have been classified, which tend to confirm the observations from the numerical model and field of jointed rock slopes. The physical and analytical fragmentation characteristics of preflawed samples are analyzed through the sieve test and fractal theory, respectively.

Ke Zhang

Chapter 3. Influence of Flaw Density on Shear Fracturing and Fractal Behavior

Abstract

This chapter investigates the influence of flaw density on the shear fracturing and fractal behavior of rock bridges in jointed rock slopes. The flaw geometry of the conceptual rock bridge model is a combination of two edge-notched flaws and imbedded flaws with different intermittent flaw densities. By numerical shear-box tests, deep insight into the mesoscopic mechanism of crack evolution is gained, and the simulated failure patterns are in accordance with experimental results. Furthermore, digital image processing and box-counting fractal analyses are performed on the shear fracture surfaces of the physical and numerical models to describe the fractal behavior. The relationships between the fractal dimension and peak shear strength are analyzed.

Ke Zhang

Large-Scale, Global Failure Mechanism and Stability Analysis

Frontmatter

Chapter 4. Empirical Methods for Estimating Strength Parameters of Jointed Rock Masses

Abstract

This chapter provides a comprehensive review of the different empirical methods for determining the strength parameters of jointed rock masses, providing the fundamental and essential information for large-scale, global slope failure studies.

Ke Zhang

Chapter 5. Kinematical Element Method

Abstract

This chapter extends the kinematical element method (KEM) to the solution of global failure mechanism. The kinematical element formulations are derived to calculate the factor of safety of slopes subjected to seismic loading and pore-water pressure. Kinematical element method (KEM) and pseudo-static approach are applied to study the effect of blasting on the stability of open pit slope, and the approach to determine the relationship between critical explosive weight and distance is presented. The seismic slope stability charts are developed on the basis of KEM and pseudo-static approach, providing a rapid and reliable way to calculate the factor of safety and the location of critical slip surface without iteration. New back analysis and reliability analysis methods based on KEM are also presented.

Ke Zhang

Chapter 6. Integrated Karst Cave Stochastic Model-Limit Equilibrium Method

Abstract

This chapter presents a new methodology for rock slope design in karst-prone ground conditions based on integrated karst cave stochastic model-limit equilibrium method. The numerical modeling and optimization design procedure contain a collection of drill core data, karst cave stochastic model generation, stability assessment and bisection method optimization. A code for karst cave stochastic model generation, named KCSMG, is developed. The stability of the rock slope with the karst cave stochastic model is analyzed by combining the KCSMG code and the SLIDE program. This approach is then applied to study the effect of the karst cave on the stability of the open pit slope, and a procedure to optimize the open pit slope angle is presented.

Ke Zhang

Chapter 7. Strain-Softening Behavior and Strength Reduction Method

Abstract

This chapter presents a method for progressive failure analysis of strain-softening slopes based on the strength reduction method and strain-softening model. The mutation is more pronounced in strain-softening analysis, and the mutation of displacement at slope crest is taken as critical failure criterion. An engineering example is provided to demonstrate the validity of the present method. This method is applied to a cut slope in an industry site.

Ke Zhang

Chapter 8. Three-Dimensional Effect and Strength Reduction Method

Abstract

This chapter investigates the failure mechanism of three-dimensional (3D) slopes by using the strength reduction method. An extensive study of 3D effect is conducted with respect to boundary conditions, shear strength and concentrated surcharge load. The results obtained by 2D and 3D analyses are compared and the applicable scopes of 2D and 3D methods are analyzed. 2D and 3D stability charts are developed, which provides a rapid and reliable way to calculate 2D and 3D factors of safety without iteration. Finally, a simple and practical calculation procedure based on the study of 3D effect and stability charts is proposed to recognize the right time to apply 2D or 3D method.

Ke Zhang

Structurally-Controlled Failure Mechanism and Stability Analysis

Frontmatter

Chapter 9. Discontinuity Kinematical Element Method

Abstract

This chapter presents discontinuity kinematical element method (DKEM) to analyze the rock slope stability controlled by major geological discontinuities. Kinematical element formulations with major geological discontinuities are derived to solve the factor of safety. Three typical failure modes of rock slope are incorporated into the DKEM. The influences of non-persistent discontinuities on rock slope failure are further investigated.

Ke Zhang

Chapter 10. Joint Element and Strength Reduction Method

Abstract

This chapter numerically investigates the fracturing process during the progressive failure of a jointed rock slope by using fracture mechanics and the strength reduction method. A displacement discontinuity method containing frictional elements is developed for the calculation of the stress intensity factor (SIF). The failure initiation of the jointed rock slope is analyzed by evaluating the SIF. A new joint model is proposed by combining solid elements with interface elements in the commercial software FLAC^3D. The progressive failure process is simulated by reducing the shear strength of the rock mass, which includes the process of stress concentration, crack initiation, crack propagation, slip weakening, and coalescence of failure surfaces. The influence of the joint inclination is investigated using the factor of safety and the SIF.

Ke Zhang

Chapter 11. Fracture Mechanics Method

Abstract

This chapter numerically investigates the evolution of an overhanging slope using fracture mechanics. A factor of safety is defined for the slope failure analysis. The progressive failure process is simulated by analyzing the propagation and coalescence of cracks through rock bridges. The influence of the joint geometry parameters is investigated based on the defined factor of safety and the calculated stress intensity factor (SIF). The approach for predicting the failure time of an overhanging slope subject to weathering processes is presented based on time-dependent weathering and the critical undercutting depth.

Ke Zhang

Titel: Failure Mechanism and Stability Analysis of Rock Slope
verfasst von: Assoc. Prof. Ke Zhang
Verlag: Springer Singapore
Electronic ISBN: 978-981-15-5743-9
Print ISBN: 978-981-15-5742-2
DOI: https://doi.org/10.1007/978-981-15-5743-9