Study On Active Earth Pressures On Retaining Walls Adjacent To Existing Basement

In the situation of a retaining wall adjacent to an exsiting basement, the width of the backfill between the retaining wall and the basement wall is limited. As the classical Coulomb and Rankine earth pressure theory are based on the hypothesis that the filling is a semi-infinite body, it is inappropriate to calculate the earth pressure in this case using the classical pressure theories. This paper focuses on numerical and theoretical studies on the earth pressure against the rigid retaining wall adjacent to the existing basement.1. FEM software ABAQUS was chosen to analyze the rigid retaining wall adjacent to the existing basement with different movement modes. The distribution of the active earth pressure of retaining wall with T mode was analyzed, the influence of the fill's width, the wall friction angle and the depth of existing basement was investigated. Further the earth pressure distribution with RB and RT modes was obtained using the same software, and the results were compared with T mode. The numerical results showed that the active earth pressure distribution, the active earth pressure coefficients, and the relative heights of the application points of the resultant earth pressure depended strongly on the wall movement modes and the ratio of the width to height of the backfill.2. Based on the previous theoretical research, a formula of the active earth pressure on the rigid retaining wall with T mode was presented without taking into account the lateral pressure from existing basement wall, but considering the effects of the wall-soil friction and the surface surcharge. The factors affecting the inclination of slip surface and the active earth pressure coefficient were discussed, and the results by the method proposed here was compared with the previous methods.3. Based on the numerical results, a new model to calculate the active earth pressure was proposed considering the influence of the lateral pressure of existing basement wall. Theoretical formulae of the resultant and the distribution of the active pressure on the T mode rigid retaning wall with cohesiveless backfill were obtained. It was shown that the magnitude of the lateral pressure decreased with the width of the backfill decreased if the wall-soil friction was not ignored, and was larger than the result obtained by the previous theory without considering the lateral pressure of existing basement wall. 4. Numerical and theoretical studies were concentrated on the active earth pressure of cohesive backfill on a T mode rigid retaining wall adjacent to an existing basement. It was shown that the adhesion between the wall and the soil could reduce the earth pressure. If the width of the backfill was fairly small and the adhesion was greater than or equal to the weight of the fill, the active earth pressure was equele to zero. It was also shown that vertical cracks appeared on both sides between the backfill and the walls, and the maximum depth of the vertical cracks did not change with the width of the fill.