Stability Analysis Of Colluvial Slope Under Rainfall

The colluvial slope refers to the accumulation of debris on the upper part of the original slope under the combined influence of internal and external forces,resulting in the collapse and collapse of the upper part of the slope,which accumulates at the lower or foot of the mountain.This article is based on the reconstruction and expansion project from Shilu Reservoir to Dengjiawan.The K2+100～K2+960 section is a colluvial slope area,mainly composed of silty clay mixed with crushed stones.The main research content and conclusions of this article are as follows:1.Experimental study on the physical and mechanical properties of colluvial deposits.Based on the large-scale direct shear test,the shear strength characteristics of colluvial materials were studied.The conclusion drawn is as follows:when the normal stress is the same,the shear strength increases with the increase of stone content.The cohesion and internal friction angle increase with the increase of stone content.The cohesion shows a trend of first increasing and then decreasing with the increase of water content,reaching its maximum value at a water content of about 10%.The internal friction angle gradually decreases with the increase of water content.2.Basic theoretical research on saturated unsaturated seepage and stability analysis of slopes under rainfall.Introduced the soil water characteristic curve,which is divided into two types:water absorption curve and dehydration curve.Analyzed the basic theory of saturated unsaturated seepage in slopes under rainfall,and derived the basic differential equation of saturated unsaturated seepage.The basic theory of rainfall infiltration was elaborated,and the shear strength theory of unsaturated soil and Morgenstern Price method were introduced in detail,laying a theoretical foundation for studying the changes in slope stability under rainfall.3.Model experimental study on slope stability analysis under rainfall action.Through rainfall model experiments,slope models with rock content of 20%,30%,40%,slopes of 30°,35°,40°,and cover layer thickness of 15 cm,25cm,and 35 cm were subjected to rainfall to study the stability and failure patterns of slopes under different working conditions.The conclusion drawn is as follows:with the increase of rainfall duration,the horizontal and vertical displacement generated by the slope gradually increase,and the pore water pressure inside the slope gradually increases,leading to a gradual deterioration of stability:When the rainfall duration is the same,the higher the rock content,the slower the slope failure speed,and the better the stability.The larger the slope,the faster the failure rate of the slope and the poorer its stability.The smaller the thickness of the cover layer,the faster the failure rate of the slope and the poorer its stability.4.Numerical simulation study on slope stability analysis under rainfall action.Establishing physical models of slopes with rock content of 20%,30%,40%,slopes of 30°,35°,40°and cover layer thickness of 3m,5m,7m,and 9m through FLAC3 D,and conducting stability analysis on them.The conclusion is as follows:as the rainfall duration increases,the slope stability gradually deteriorates,with a slower decline in the early stage and a faster decline in the later stage of rainfall.When the rainfall duration is the same,the higher the rock content,the slower the slope failure speed,and the better the stability.The larger the slope,the faster the failure speed of the slope and the poorer its stability.The smaller the thickness of the cover layer,the faster the failure rate of the slope and the poorer its stability.The results obtained are mutually verified with the model test results.