Stability Analysis of Clastic Rock Slope with Mudstone Interlayer Under Rainfall Infiltration

Abstract

The clastic rock slopes with mudstone interlayer are widely distributed in Guangxi, China. The mudstone interlayer is less permeable than the clastic rock, that may cause slope instability during the rainfall condition. In this study, a numerical analysis was conducted to study the effect of mudstone interlayer on clastic rock slope stability. A two-dimensional slope seepage model based on fluid–solid coupling was developed for the stability analysis of clastic rock slope with mudstone interlayer under different rainfall conditions. Rainfall-induced change of soil matrix suction in slope was analyzed by unstable seepage analysis and the effects of matrix suction on the slope stability and slip surface were then considered. Results indicated that the mudstone interlayer in clastic rock slope could develop to be the slip surface easily and made the clastic rock slope easy to fail under rainfall condition. When the soil matrix suction near the mudstone interlayer surface reaches a certain threshold value caused by rainfall intensity and duration, the most dangerous slip surface moves to the superficial layer, and the slope stability has a sudden drawdown.