Horizontal Bearing Characteristics of Pile Group Foundation with Composite Pile-Cap Connection

[Purposes] Two types of pile group with different pile-cap connection forms (1×3 pile group with ordinary connection and 1×2 pile group with rigid connection) are tested in the field to obtain and the influences of connection stiffness and the number of piles on their horizontal bearing capacities. [Methods] On this basis, the finite element method was used to study the influence of connection stiffness on its bearing capacity. Besides, the composite connection pile groups with different connection forms were used to study their bearing capacities and load distribution mechanism. [Findings] The results show that the average ultimate bearing capacity of foundation piles can be increased by about 17.63% and the horizontal displacement can be reduced by 41.64% by using 1×2 rigid connection group piles. After adding T-shaped steel members, the vertical deformation capacity can be increased by up to 54.22%, and the connection rotation can be improved. For the front bearing pile, the anchoring steel bar can be cancelled and a larger embedded depth can be selected. The overall horizontal stiffness of the pile group with composite connections can be increased by up to 13.07%, and its vertical deformation capacity can be improved at the some time, which is conducive to the uniform distribution of horizontal load in the later stage of loading. The connection stiffness of pile should be determined by the connection stiffnesses of both the pile and its adjacent pile.