Engineering Characteristics Of Basalt Residual Soil In Southwest Mountainous Area Slope Stability Analysis

With the proposal of the national balanced economic development strategy,the transportation infrastructure construction in southwestern mountainous areas of China has developed rapidly.Under the interference of special geological,climatic environment and human factors in the region,natural or artificial slope collapse and landslide accidents occur frequently,which not only cause huge economic and environmental damage,but also adverse social impacts.In this thesis,the Yi-Yi highway project under construction is taken as the background,and a basalt residual soil slope is taken as the research object.The engineering characteristics of basalt residual soil are studied by laboratory test,theoretical analysis and numerical simulation.On this basis,the influence of excavation and rainfall strip on slope stability and its prevention measures are analyzed and discussed.The main conclusions are as follows:(1)Physical property test results show that basalt residual soil is high liquid limit clay,liquid limit is as high as 80.4%,plastic limit is 50.7%;free expansion rate as high as 96.5%,strong expansive soil;the clay mineral composition of montmorillonite and kaolinite in basalt residual soil accounts for about 52.1% of the total.In the natural state,the microstructure of the soil is mainly flocculent and agglomerate structure,the internal structure is loose and contains a large number of pore structure,which makes the basalt residual soil show high liquid limit and strong expansion.(2)With the decrease of dry density,the increase of water content and the increase of overlying load,the expansion of basalt residual soil gradually weakens.By analyzing the quantitative relationship between expansion deformation and dry density,water content and overlying load,the prediction expansion rate formula of basalt residual soil in southwest mountainous area is obtained by fitting.(3)The compressibility of basalt residual soil decreases with the increase of dry density;the soil has high strength when dry,and the strength decreases rapidly with the increase of water content,and the water stability is extremely poor.The microstructure of remolded basalt residual soil under different dry densities was quantitatively analyzed by IPP software,and the relationship between macroscopic mechanics and total pore area of microstructure was established.(4)Combined with engineering examples,the influence of water content change and slope ratio change on stability is analyzed;the reasonable treatment measures of the residual soil slope are determined by calculation and analysis.On this basis,the prevention measures of similar slope are summarized,which provides reference for the protection and prevention of basalt residual soil slope.