ABSTRACT:

By means of introducing strength reduction method and gravity increase method to particle flow code, the stability of the jointed rock slope is analyzed. In the analysis, rock is described by the particles and their contacts, and joints by the smooth joint model. Meanwhile, there is no longer need predefined constitutive relation or presupposing sliding surface. After strength reducing or increasing gravity, the fractures generate, propagate, and coalesce along the contacts with minimum tensile or minimum shear strength, forming the final sliding surface. Comparing with traditional limit equilibrium method, the result of particle flow code is more reliable in obtaining the safety factor and has more advantages in determining the sliding surface. It will provide a new approach for the stability analysis of jointed rock slope.

1 INTRODUCTION

After repeated geological action, rock mass in slope primarily composes of rock and structural surface. The structural surface can divide into bedding plane, joint, crack and fault fracture zone, due to its structure, occurrence, and characteristics (Chen 2005). The rock mass is cut into structures with different sizes, shapes for the presence of structural surfaces, as a result, it exhibits discontinuity. What's more, the rock strength is always determined by the structural surfaces because of their extremely low strength properties. Specially, joint is one of the important structural surfaces.

The main methods analyzing slope stability are traditional Limit Equilibrium Method (LEM), Finite Element Method (FEM), Discrete Element Method (DEM), etc. LEM is mainly applied to homogeneous slopes (Bishop 1955). This method requires pre-defined sliding surface shape and location with artificially, and it does not consider the relationship of sticks' stress and strain. FEM has considered the stress and strain relationship, and can qualitative evaluate the slope stability according to nodes' displacement and plastic strain zone. In recent years, Zheng & Zhao (2004) incorporated strength reduction method and gravity increase method into FEM, which not only calculated the safety factor, but also showed the sliding surface corresponding to the minimum safety factor.

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