Active Earth Pressure against Cantilever Retaining Wall Adjacent to Existing Basement Exterior Wall

The theory and model tests for active earth pressure on a cantilever pile wall adjacent to existing basement exterior wall are studied in this paper, taking noncohesive sand as the research object. The ultimate rupture angle is presented with the global static equilibrium method based on the movement mode of a flexible retaining wall rotating about the base and the plane sliding surface. The soil arching theory is introduced to obtain the coefficient of active earth pressure in the subarea, in which the trajectory of minor principal stress after stress deflection is assumed to be a circular arc. Taking account of the effects of shear stress between differential level layers and the nonlimit state of the lower soil layer, the differential level layer analysis method is modified and the solution for the unit earth pressure, the resultant force, and the height of action point of the resultant force are derived. The model tests are conducted to simulate the deformation and the progressive failure process of the sand with limited width under the movement mode of the flexible retaining wall rotating about its base. Analysis and processing of the images observed from the model tests was compared with the rupture angle calculated with the proposed method and showed that the method can provide a good prediction. The lateral earth pressure decreases with the decrease of the ratio of width to height in the critical width range. Considering the effects of the nonlimit state and the partial mobilization of the shearing resistance of the lower soil layer, the internal friction angle has been reduced based on shear strength reduction theory, consequently the calculated lateral earth pressure agrees with the measured result from model tests. The upper part of the theoretical distribution curve is close to a linear line and the lower part is a concave upward nonlinear curve while its distribution law is the same as the measured curve. The action point of the resultant force under the movement mode of rotation about the base is located at the height of 0.27–0.31 wall within infinite width sand filling.