In Situ Tests on Cast-in-Place Concrete X-Section Pile for Bearing Capacity of Single-Pile Composite Foundation

The static load tests for pile composite foundation of X-section pile and circular section pile in the same area are conducted on trial pile in soft soil reinforcement engineering of a sewage treatment plant in the North of Nanjing, China. The load-settlement curves, pile-soil stress ratios and distributions of axial force are obtained. The comparison of test results on single-pile composite foundation of the two indicates that the vertical bearing capacity of X-section pile is 20% greater than that of the circular section pile with the same use of concrete because of the larger side friction. The results also show that the pile-soil stress ratio of X-section pile is higher than that of circular section pile, and the settlement of circular section pile is larger than that of X-section pile under the same loading. The axial forces of both X-section pile and circular section pile decrease from the pile top to the bottom. Therefore, in the same area, the bearing capacity of single-pile composite foundation of X-section pile is better than that of circular section pile. The in-situ test results are very significant for the theory study and engineering application of X-section pile composite foundation.