At present

the method of uniform isometric piles is used in most group pile designs. This method has major defects in foundation stress and deformation. Considering the increase of group pile foundation stiffness and reducing the differential settlement of group pile foundation

the group pile foundation displacement function is combined with the pile length optimization function. Under the method of line transformation and squared transformation

different group pile designs are determined by setting different pile length ratio ξ and connection curvature η. The scheme is used to analyze the variation law of axial stiffness ratio and differential settlement ratio of group pile foundation under different schemes. The reliability of theoretical analysis results is verified by finite element method. In addition

parametric analysis of axial stiffness ratio and differential settlement ratio of pile group foundations are based on different pile-soil stiffness ratios and different pile spacings. The results show that the optimal transformation mode of different pile groups and different pile lengths have different effects on the optimization results of group pile foundations. When the optimization purpose is to increase the pile group foundation stiffness

the optimization method of line transformation should be chosen. When the optimization purpose is to decrease the differential settlement of pile group foundation

the optimization method of squared transformation should be chosen. The axial stiffness of pile group increases with the increasing of pile-soil stiffness ratio and the decreasing of pile spacing. The differential settlement ratio of pile group decreases with the increasing of pile-soil stiffness ratio and the decreasing of pile spacing.