Experimental Study On Erosion Process And Influencing Factors Of Granite Residual Soil On Composite Slope

The Collapse refers to the erosion phenomenon of soil and rock mass on hillside which is destroyed under the combined action of hydraulic and gravity.Soil erosion caused by Hill Collapse in mountainous and hilly areas with more rainfall in southern China has seriously endangered the production,living and ecological environment of local people.With the state attaching great importance to the ecological environment construction and large-scale implementation,a series of research achievements have been made on the mechanism and influencing factors of hill collapse erosion.In this paper,the granite residual soil in Yudu County of Jiangxi Province is taken as the research object,and the following aspects of research work are carried out:(1)By consulting a large number of literature,the mechanism and influence of slope collapse erosion under rainfall conditions are summarized.Based on the natural environment and soil condition of granite residual soil in southern Jiangxi Province,the erosion mechanism of granite residual soil is studied from three factors: rainfall intensity,soil moisture content in early stage and soil thickness on slope.(2)A model device is designed,which includes three main systems: main flume,artificial rainfall simulation system and data acquisition system.The model can simulate the process and morphological evolution of rain infiltration and Hill Collapse erosion on composite soil slopes under indoor rainfall conditions.(3)Through the experiments of rainfall intensity of 100mm/h,125mm/h and150mm/h,it is concluded that the erosion and destruction generally presents the process of rainfall-splash-sheet Erosion-Rill Erosion-Gully erosion.The failure modes of slope surface are different under different rainfall intensity tests.During the100 mm/h and 125 mm/h rainfall intensity tests,block failure occurred on slope and gully failure occurred under 150 mm/h rainfall intensity.(4)Through the experiments of soil moisture content of 7% 11% and 15% in the early stage,it is concluded that the soil moisture content in the early stage will affect the distribution of infiltration and runoff in the process of rainfall.The largerthe water content in the early stage,the larger the self-weight of the soil,the weaker the strength of the soil,thus affecting the time and location of the collapse.(5)Through the tests of 200 mm,300 mm and 400 mm soil thickness,it is concluded that the greater the soil thickness,the greater the water absorption capacity and the more time it takes to reach saturation,the more serious the damage will be.(6)The infiltration process of soil under 100 mm/h rainfall intensity was simulated by COMSOL Multiphysics.The simulation data of water content in three sections of slope,middle and foot were selected.The results showed that the water content of foot of slope increased fastest,followed by the position on the slope,the slowest was the position on the slope.This result was consistent with the wetting peak descending process monitored during the test process.The simulation effect was in accordance with the test conclusion.The results are consistent.