Study On Soil Arching Effect Behind Antislide Pile In Completely Weathered Granite Slope

Completely weathered granite residual soil slope has a wide distribution in the south of China.This slope retains or partly inherits other rock features,eg structural plane of the original rock,etc and without a secondary deposit, and also has stability characteristics that is significantly different from the homogeneous soil slope and rock slope. And has a high friction angle, the structural engineering Supporting and Retaining in the anti-slide piles will form soil arching effects.This paper use model test, numerical simulation and theoretical analysis for study of soil arching effect of this slope and its main affecting factors research, results obtained are as followings:(1) Based on-site survey,the completely decomposed granite residual soil slope can be divided into four types according to the slope structure assemblage characteristics, and summed up several different failure mode of this soil cutting slope type.(2) Conventional physical model test method is proposed for soil arching effect study, and test instrument is developed. According to model experiments combined with numerical simulation study, the characteristics of completely decomposed granite residual soil slope arching effect and its impact factors is presented.Also the relationship between the soil arch height and pile spacing,pile width,soil properties is analyzed. The results indicated that soil arching height is maily affected by pile spacing and soil friction angle.while pile width determines the arch thickness which affecting the strength of soil-arch-arch body, thus affecting the strength of soil arching effect. Soil arching height is little affected by cohesion of the soil, but the soil-arch-arch body strength can be affected thus affecting the strength of soil arching effect.(3) Based on the Bo Prandtl-Vesic foundation bearing capacity theory,the calculation method of soil arching shape and arching height is proposed.lt is confirmed that soil arch can be considered as an isosceles triangle shape, and its functional equation is presented. The height of soil arching in Completely weathered granite residual soil slope is calculated with this theory.Compared with the model test result, it is concluded that this method is feasible.(4) Based on the experimental result,it can give euidance to the design of pile and structure between pile on the completely weathered granite slope.