Evaluating the Effects of Soil Softening on the Stability of Soil-Rock Slopes with Various Bedrock Surfaces

ABSTRACT The aim of this paper is to investigate the stability of soil-rock slope with different softening conditions and bedrock surfaces. More than 3,000 2-D stability analyses were performed using a strength reduction limit analysis method. A stochastic generation method based on the function distribution was introduced to consider the spatial random distribution of rock blocks. For each kind of softening condition and bedrock surface, 10 different rock blocks arrangements had been made. The results showed when the overall soil strength is reduced by 20 %, the safety factors of soil-rock slopes with different types of bedrock surfaces decrease by more than 20 % under each volumetric rock block proportion. When the strength of the contact zone soil is reduced by 40 %, the maximum reduction of safety factors is about 20 % compared to that of nonsoftening slopes. The reduction rate of the average lower limit safety factor decreases gradually as the thickness of the softened contact zone increases. There are significant differences in the influence of bedrock surfaces on the stability of soil-rock slopes under different soil softening conditions. The graphs obtained could be used for guidance in the project with soil-rock slopes.