Test research and numerical simulation analysis of long-short piles composite foundation

Based on a series of static loading tests on single pile,single-pile and four-pile composite foundation at certain expressway test section in Zhengzhou,the load-bearing capacity of rigid pile composite foundation is numerical simulated and compared in detail.The results show that the pile-soil stress ratio increases with the increasing of the number of piles and pile depth.And in the long-short-pile composite foundation,the pile-soil stress ratio of the long piles is higher,indicating that the load shared by soil between piles decreases accordingly.Moreover,the settlement deformation of four-pile composite foundation is higher than that of single-pile composite foundation because of pile group effect.The comprehensive influence coefficient of pile group is 0.578,and it increases with the increasing of pile depth.