Date of Award

2015

Document Type

Thesis

Publisher

Edith Cowan University

Degree Name

Master of Engineering Science

School

School of Engineering

Faculty

Faculty of Health, Engineering and Science

First Supervisor

Associate Professor Sanjay Kumar Shukla

Second Supervisor

Dr Hang Vu

Abstract

Slope stability in mining and civil engineering projects is always a problem of great concern. Because the rock mass behavior is significantly governed by the presence of joints or other discontinuities, several types of slope failure, such as plane failure, wedge failure, toppling failure, buckling failure and circular failure, are often observed. The present work focuses on the study of the wedge failure, which occurs as sliding of a mass of rock on two intersecting planes, generally discontinuity planes.

Recently, the factor of safety of rock slopes against the wedge failure has been studied in a number of investigations under static and/or dynamic conditions by different methods such as the limit equilibrium method, numerical modeling method, reliability method and stereographic method. However, the anchored rock slope against the wedge failure subjected to surcharge and seismic load has not yet been studied in detail in earlier studies. In this thesis, the rock slope subjected to the generalized loads such as surcharge and seismic/dynamic loads is analyzed against the wedge failure by the limit equilibrium method. The expression for the factor of safety was derived for the cases with anchors and without anchors separately. In addition, a parametric study is carried out to demonstrate the effects of the most relevant governing parameters on the stability of rock slope. The parameters include geometrical parameters, joint material properties, unit weight of rock, anchor inclination and hydraulic parameters. Several special cases of the developed generalized expression result in the expressions for the factor of safety for simplified field situations as reported in the literature.

The parametric study shows that most parameters as mentioned above affect the factor of safety ( FS ) of the rock slope against the wedge failure significantly. In order to find an easy way to work on the parametric analysis, the “ * ” indicates dimensionless parameters. It is observed that the surcharge would always be a destabilizing force when the cohesion (c* ) is not zero; the FS decreases with an increase in surcharge. However, when c* = 0, the FS increases slightly with an increase in surcharge. The anchor forces (T* ) would always be a stabilizing force that makes the FS increase with an increase in T*. As the angle of inclination of the joint plane/failure plane to the horizontal ( p y ) increases, the FS increases nonlinearly; it increase sharply by 60% from 42° to 45° while it deceases nonlinearly by 67% with an increase in the slope angle (yf ) from 40° to 60°. It is also observed that the FS decreases with an increase in horizontal seismic acceleration coefficient (k h ) and the vertical seismic acceleration coefficient (k v ), separately, while it increases linearly with an increase in the following parameters: the cohesion (c* ) and the angle of shearing resistance ( f ), separately. The FS increases with an increase in inclination of stabilizing force to the normal at the failure plane (a ); it becomes maximum when a increases to 80°. However, the unit weight of rock (g* ) does not affect the FS significantly.

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