Abstract:In order to analyze the influence of stiffness on the behavior of raft foundation, an analysis model of interaction between raft foundation and foundation soil has thus been established by using FLAC3D finite difference software. With the other parameters of the model a constant value, eight kinds of numerical simulation calculation are to be carried out by changing the rigidity of raft foundation, thus obtaining the variation rules of the maximum vertical stress, the maximum settlement and the settlement difference of raft foundation, followed by an analysis of the influence of the column group effect of superstructure on the maximum vertical stress and the maximum settlement of raft foundation. The calculation results show that when the settlement of raft foundation is too large and fails to meet the requirements of the code, there is an upper limit value of the rigidity to reduce the settlement of the foundation by increasing the rigidity of raft foundation. When the raft foundation rigidity reaches the upper limit, the effect is not obvious, however, of increasing the foundation rigidity on reducing the settlement. Moreover, if the uneven settlement of raft foundation tends to be too large, the method of increasing the foundation stiffness will achieve ideal results. The upper limit value of the rigidity to reduce the foundation settlement is not equal to the value of the rigidity to adjust the uneven settlement, with an optimal rigidity value between the two. Therefore, the deformation and economic benefits should be taken into a comprehensive consideration in the engineering design. In view of the insignificant effect of group column on the maximum vertical stress of raft foundation, and without considering the effect of group column, the maximum settlement of raft foundation will be overestimated.