Research On Landslides Mechanism Induced By Rainfall

Landslides induced by rainfall is a dynamic process.As rainwater Penetration into the soil, water content and bulk density was increased while soil is softened and the shear strength was reduced.This article studied the relationship between landslides and the coupling effect of rainfall and topography through analyzing the data of rainfall and landslides of the Southwest four provinces (mainly in Sichuan, Chongqing, Yunnan, Guizhou) and the Three Gorges reservoir area, based on previous studies. The achievements were obtained as follows:(1)Summarizing the theoretical knowledge of landslides induced by rainfall, analyzing the basic conditions for the formation of landslides, obtaining the inducing mode of landslides induced by rainfall based on the two factors of the formation of landslide(internal factors and triggering factors), studying the changing mechanism of soil mechanics parameters with water under different conditions of terrains and lithology, the load changing mechanism of slop under pore pressure and changing mechanism of slop structure and topography under rain erosion.(2) The three-dimensional control equation of unsaturated seepage under rainfall conditions was derived and the definite solution condition was given, through introducing the basic theory of saturated-unsaturated seepage under rainfall conditions and using the Darcy’ law. Through analyzing the finite element method for solving the unsaturated soil two-dimensional seepage control equation, the solving method for control equation was obtained and the finite elements model was established for the next numerical simulation of seepage.(3)Through studying the spatial and temporal distribution characteristics of rainfall and landslides in China, analyzing the relationship between rainfall and landslide density, the consistency and hysteresis relationship on time about rainfall and landslides, the V-A relationship between rainfall and landslides, the rainfall threshold in Southwest was obtained. The relationships between rainfall and water content, water content and shear strength, cohesion, internal friction angle of soil were obtained by analyzing the experimental data. Finally, the article analyzed the correlation between rainfall and Siguanzhai landslides.