Influences of a Rainfall on the Stability of Granite Residual Soil Slopes

Abstract

Observations showed that an overwhelming majority of landslides occurred during or after a rainfall. Infiltration of rainwater into slope would increase weight of the slope, change pore water pressure in the slope, and reduce shear strength of the soil. In an unsaturated soil slope, the matrix suction, which could be regarded as negative pore water pressure, was one of the major factors that influenced the stability of a slope. The influences of a rainfall on negative pore water pressures and the stability of a slope have been analyzed in this paper by simulating negative pore water pressure distribution of the slope under various rainfall intensities, with the help of a finite element software— GEO-SLOPE-SEEP/W. The importance of matrix suction to the stability of a slope was elaborated through the calculation of a granite residual soil slope project. Results showed that the safety factor of a slope was obviously underestimated if no matrix suction was considered. It differs much from the actual case.