Influences of column cap on progressive failure and stability characteristics of column-supported embankments

The design of cap in rigid columns, which has been widely used in engineering practice, can avoid the stress concentration at the column top and enhance the performance of composite foundation. However, the effects of the cap on the stability and progressive failure of rigid column-supported embankment is relatively lacking. A finite difference numerical model is established to simulate the behavior of rigid columns with cap. The influences of the cap on the stress and failure mode of the columns under embankment loads are analyzed, and those of different cap sizes on the stability of embankment are compared. The results show that the tensile stress and the bending moment decrease significantly when cap is used, and the critical failure mode is bending failure. Compared with that of the case without cap, the continuous failure of the case with cap is more obvious. An increase in the cap size can effectively reduce the loads on the columns and improve the stability of the embankment, but there is a risk of cap damage. Therefore, it is necessary to estimate the bearing capacity of the cap in the design.