Complex Failure Simulation of Underinclined Shale Slope Based on Discrete Element Method

Bin Li,Da Huang

doi:10.15446/esrj.v24n1.85397

Abstract

A landslide occurred in the cut slope located in Chongqing west railway station, this slope belongs to a under-dip shale slope, which means that its bedding dip angle is larger than slope angle and it is comprised of soft rock. Some on-site investigations have been made to explore the deformation characteristics of this slope, the outcome suggested that sliding, buckling and toppling deformation existed at its different parts. To elucidate the complex failure mechanism exhibited by the under-dip slope under the long-term influence of gravity and material deterioration, the discrete element method has been employed in simulations. The simulated failure patterns have proven to be in strong agreement with the actual slope failure. This study suggests that sliding, buckling and toppling occur at different parts of the studied slope in sequence.

Highlights

This paper describes and analyses the complex failure of an under-dip shale slope discovered in Chongqing west Railway Station, which involves three mechanisms: sliding in the upper part, buckling in the lower part and toppling at the toe.The bedding dip angle (68°) of the slope is larger than the slope angle (45°) and it is comprised of shale
This study explored the complex failure mechanism of a shale underdip slope based on an on-site investigation and numerical analysis
It has been proved that the under-dip slope has a complex deformation process in which sliding, buckling and toppling failure occurs sequentially at its different parts

Summary

Introduction

This paper describes and analyses the complex failure of an under-dip shale slope discovered in Chongqing west Railway Station, which involves three mechanisms: sliding in the upper part, buckling in the lower part and toppling at the toe. For the local slope suffering buckling failure, the bedding plane dips 68°, the actual slope length is 10.8m, the elasticity modulus E is 1500MPa, the thickness of the layered rock mass is 0.1m, when K=1.0, the equivalent friction angle of the bedding plane φ equals 14.5°.The stability of the slope is estimated based on the limit equilibrium method, the factor of safety is 0.8 when the equivalent friction angle of the bedding plane φ equals 14.5°, While the calculated factor of safety of the slope approximately equals 1.0 when cohesion c is 12kPa and friction angle φ is 10°, so the ultimate mechanical parameters of joint sets from back analysis is c=12kPa, φ=10°.Table 3 describes the parameters for relevant materials included in the UDEC model for the rigid blocks and contacts. Parameters Density(kg/m3) Normal stiffness(Pa/m) Shear stiffness(Pa/m) Cohesion(kPa) Friction angle(°) Tensile strength(kPa) shale 2427 5e9 2e9

Results and discussion

Conclusion