Study On Subgrade Stability Of Slope Soft Foundation In Mountain Areas

In southwest of China,highway constructed in the slope soft foundation often have the engineering diseases such as uneven settlement of subgrade,basal slip or subsidence,landslide and collapse of the cutting slope. With the development of the transportation, more and more highway have to be constructed on such foundation. In order to guarantee the stability of the subgrade,the structural integrity of the pavement and better service for the road, the research on the slope soft foundation in mountain areas needs to be enhanced.In order to solve the stability problem of the subgrade in the slope soft foundation, the paper uses the finite element strength reduction method and orthogonal experimental design to analyze the stability of the subgrade in the slope soft foundation,the influence of hard shell layer on the embankment stability in the slope soft foundation,the stability of the cutting slope in the slope soft foundation,and have the regression analysis on the stability coefficient.1) The paper has analyzed the factors on the stability of the subgrade and the main types of project situation in the slope soft foundation, established finite element model to analyze the stability of the subgrade in the slope soft foundation.Throughing the above calculation,the paper has proposed relation formula between embankment stability coefficient and gradient of slope,soft soil thinkness,embankment height,embankment filling cohesion and internal frictional angle,soft soil cohesion and internal frictional angle.After that,the relation formula has been verified in the project cases.2) The paper has established finite element model to analyze the stability of the subgrade with hard shell layer in the slope soft foundation,analyzed the influence law of hard shell layer on the embankment stability in the slope soft foundation and presented the engineering condition in which hard shell layer provides good effects on the stability of the subgrade.3) The paper has established finite element model to analyze the stability of the cutting slope in the slope soft foundation,proposed relation formula between stability coefficient and gradient of slope,cutting height,soft subsoil thinkness,soft soil cohesion and internal frictional angle.The relation formula has been verified in the project cases and have good results. This article's results have provided a theory reference for the study on stability of the subgrade in the slope soft foundation, which also provide practical formulas for the subgrade stability analysis of the slope soft foundation in southwest of China.