Rock-socketed piles can hardly be loaded to failure in field tests due to their high ultimate bearing capacity. In order to investigate the pile resistance behavior along the concrete-rock interface, two rock-socketed pile models were tested in laboratory. One model was loaded to failure at the maximum applied load. It was observed that the slippage occurred along the concrete-rock interface, while the pile body and the rock mass remained intact. The mobilized pile resistance along the concrete-rock interface within the rock-socketed section was evaluated from the recorded axial strains. The results indicated that the shaft resistance was not evenly mobilized within the socket. It is clear that the mobilized pile resistance in the upper zone is much greater than that in the lower zone. In addition, a serious of numerical simulations of tests were performed by using a finite element program. The interfacial elements were adopted in the program to model the concrete-rock interface behavior. The numerical analyses indicated that notable normal stress could be produced along the concrete-rock interface due to the lateral deformation in the rock mass. The mobilization of the pile resistance along the interface was greatly influenced by the normal stress. Therefore, the mobilized pile resistance in the upper zone is much greater than that in the lower zone. The investigation suggests that the pile resistance behavior along the concrete-rock interface can dominate the working performance of the rock-socketed piles constructed in hard rocks. Furthermore, the pile resistance along the concrete-rock interface can be greatly influenced by the deformation characteristics of rock mass.
Chinese Journal of Rock Mechanics and Engineering