Abstract:
Submerged toe walls are frequently used in high concrete face rockfill dams. At present, the distribution and variation of earth pressure on the back of a submerged toe wall during construction and impounding periods are not clear. In this study, a simplified 2D plane strain finite element model for a concrete face rockfill dam with a 10-m toe wall is used to investigate the distribution and variation of the earth pressure on the back of the toe wall. The contact mechanics approach is employed to model the interface behavior between the toe wall and the rockfill. The numerical results show that after impounding the normal stress along the upper part of the contact surface decreases gradually while that along the lower part undergoes a slight increase. The normal stress exhibits a parabolic distribution, with the peak presents near the center of the interface. The shear stress increases with the increasing friction angle of the contact surface, and the range of the contact surface reaches the ultimate shear stress gradually decreases. The toe wall displaces upstream during construction, accompanied with a rapid increase in the normal resultant force. The shear force, on the other hand, decreases to 0 initially and then increases rapidly during the following construction stages. The earth pressure coefficient
K obtained by the FEM is 4.9~5.4, which is between the maximum
Ka and the minimum
Kp from the Coulomb's earth pressure theory. Therefore, there exists a certain error in terms of the earth pressure on the toe wall calculated by the traditional earth pressure theory. The traditional theories are not suitable for the evaluation of stability and stresses of submerged toe walls.