Impact of Crack on Stability of Slope with Linearly Increasing Undrained Strength

Bing Li,Di Wang,Fei Zhang

doi:10.1155/2018/1096513

Bing Li, Di Wang + Show 1 more

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https://doi.org/10.1155/2018/1096513

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Abstract

This paper presents a procedure for assessment of the impact of tension crack on stability of slope in clays with linearly increasing undrained strength. The procedure is based on the limit equilibrium method with variational extremization. The distribution of the normal stress over slip surface is mathematically obtained for slopes in clays with the linearly increasing undrained strength and then used to determine the tension crack for clays with zero tensile strength. The seismic effect is also included using the pseudostatic approach. Closed-form solutions to the minimum safety factor and the maximum crack depth can be derived and given in the form of chart for convenient use. The results demonstrate a significant effect of the tension crack on the stability of steep slopes, especially for strong seismic conditions. In this situation, neglecting the impact of tension crack in traditional ϕ=0 analyses may overestimate the slope safety. The most adverse location of the tension crack can be also determined and presented in the charts, which may be useful in designing reinforcements and remedial measures for slope stabilization.

Highlights

Slopes in clays are usually under short-term undrained conditions, such as slopes at the end of construction, slopes subjected to earthquakes, and rapid excavations
This paper presents a procedure for assessment of the impact of tension crack on stability of slope in clays with linearly increasing undrained strength
Neglecting the impacts of tension crack, the closedform solutions are in good agreement with the limit equilibrium (LE) results of Koppula [6]

Summary

Introduction

Slopes in clays are usually under short-term undrained conditions, such as slopes at the end of construction, slopes subjected to earthquakes, and rapid excavations In these situations, the traditional φ = 0 limit equilibrium (LE) analysis is carried out to assess the stability of slopes. Gibson and Morgenstern [2] adopted the linear increasing undrained strength with cu0 = 0 into the φ = 0 analysis and established an expression to calculate the factor of safety. Yu et al [11] used finite-element LA method to calculate the lower- and upper-bound solutions and compared with LE results from the φ = 0 analysis. Their solutions were given in the form of charts for convenient use in practice. Chai et al [14, 15] employed the finite-element (FE) method to back analyze the failure of an embankment on clay deposit

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