Experimental And Numerical Simulation Study On 3D Passive Slip Surface Behind The Rigid Retaining Wall Under The Mode Of Translation

The spatial effect of slip surface behind the retaining wall is the objective existence.The study on the spatial form of slip surface is of fundamental significance for the theoretical analysis of 3D earth pressure.The model test device is designed and carried out for 6 groups of test.The exact form of the slip surface is obtained by monitoring the position where the brittle glass strip broke.And the projection form of the slip surface in the principal plane and the soil uplift form are analyzed.100 experimental conditions are calculated to analyse the relationship between slip surface spatial form,principal plane projection form and width depth ratio of the retaining wall,soil internal friction angle,roughness of interface between retaining wall and soil,by the numerial simulation method,using single factor control variable method.The following results are obtained:(1)The 3D passive slip surface is obtained by the method of test and numerical simulation.The width of transverse section of slip surface is larger than that of the retaining wall.With the increase of the distance from the retaining wall,the width of the horizontal section at the bottom of the transverse section decreases gradually,the height of the lowest part of the transverse section increases gradually,the shape of transverse section gradually changed from the shape "U" to the shape "V".The second part of the longitudinal section of the slip surface is approximately a straight line,and there is a slight difference between the longitudinal sections.(2)The projection form of the slip surface on the principal plane is obtained.Firstly it is extended linearly with initial diffusion angle from the bottom of the retaining wall.The most distance from the retaining wall is parallel to the retaining wall,but the width is less than the width of the retaining wall.And the diagonal and horizontal line is connected with arc.The projection form of principal plane is perpendicular symmetry about retaining wall.(3)The influence factors of the spatial form of the slip surface are analyzed and summarized.(1)With the increase of the width depth ratio of the retaining wall,the spatial characteristics of the slip surface are not obvious,and the fracture angle of the longitudinal section of the slip surface decreases.(2)With the increase of the soil internal friction angle,the fracture angle of the straight section of the longitudinal section of the slip surface decreases gradually,the height of the bottom of the transverse section decreases gradually,the width of the principal plane projection and the distance from the retaining wall increases linearly.(3)The roughness of interface between retaining wall and soil has smaller effect on the form of slip surface and principal plane projection.(4)The displacement of the soil getting to the passive limit failure is gained.As for cohesionless soil,the displacement of the retaining wall is about(10%~12%)H,while the retaining wall is limited width depth ratio and under the mode of translation and the soil achieved passive limit state.