Structural Capacity of Precast Piles with Grouted Base

To improve the performance of a precast pile installed in a prebored hole, a grouted base is often made around the base of the pile. The structural capacity of a precast pile with a grouted base was studied by three series of model loading tests. Two failure mechanisms were observed, punching failure and splitting failure, which depended upon the geometry of the grouted base. Punching failure occurs in cases in which the grouted base is thin, less than twice the pile diameter. In contrast, splitting failure develops in cases in which the grouted base is thicker than twice the pile diameter. Structural capacity increases with increasing the thickness of grouted base. The effect of diameter of grouted base was also examined. Based on the experimental observations, a theoretical model was developed to evaluate the structural capacity. The theoretical prediction agreed well with the experimental results. A parametric study was performed to determine the optimum shape and strength of the grouted base.