Study On Rainfall Infiltration Mechanism Of Slope Gravelly Soil In Qinba Mountain

Geological disasters caused by rainfall have a great impact on people's life and property safety in Qinba mountain area every year,As a typical landslide medium in this area,slope gravelly soil is very easy to form geological hazards under the effect of rainfall.Because of the complexity of the composition and the difference of the structural state of the gravelly soil,it is difficult to study its rainfall infiltration law,and its infiltration mechanism is often difficult to explain systematically.Based on the National Natural Science Foundation of China "Research on rainfall infiltration stability evaluation method of shallow gravel soil landslide based on GIS" and China Geological Survey Bureau "geological disaster investigation of Renhe River Basin in the middle reaches of Hanjiang River",in order to explore the rainfall infiltration mechanism of slope gravel soil in Qinba Mountain Area,this paper takes the gravel soil slope of Bamiaozhen Shazhiliang landslide as the research object,Based on the field regional geological survey,the indoor test work is carried out,and the rainfall infiltration mechanism of this kind of soil is systematically studied by combining the theoretical research and numerical simulation,and the following results are obtained:(1)The unsaturated characteristics of remolded gravel soil were studied by dehumidification and humidification tests under different void ratio and gravel content.The V-G curve model was fitted by MATLAB software,and the effects and rules of two factors on soil water characteristic curve and fitting parameters were analyzed;(2)The fitting results of V-G curve model and V-G unsaturated permeability model are applied to mein Larson rainfall infiltration model,and the improved rainfall infiltration model parameters for gravel soil under different void ratio and gravel content in Qinba mountain area is obtained;(3)Through the finite element simulation software Geo-studio to simulate the rainfall infiltration process of the gravel soil under the layered state,the infiltration forms of the strong permeable boundary and the water barrier boundary of the single-layer soil are discussed,and the rainfall infiltration modes of the double-layer soil under different rainfall conditions and soil layer combinations are described in stages.