Numerical Analysis on Group Pile Effect of Pressure Grouted Helical Pile Group

Helix Stiffened Cement Mixing Pile (HSCMP) is a new type of composite pile, and its group pile effect and bearing capacity variation law is still unclear. Based on the finite element numerical simulation method, the ratio of HSCMP pile spacing to helix diameter (S_g/D_H) and the ratio of cement soil strength to soil strength around the pile (C_ref/S_u) were parametrically analyzed and the results were compared with the theoretical calculation of the group pile effect coefficient. The results show that the group pile bearing capacity is positively correlated with soil strength and pile spacing when the helix diameter and soil properties are kept constant; when S_g/D_H≤2, the existing theoretical calculation results are similar to the numerical simulation results, and the numerical simulation results are more consistent with the stress superposition method as S_g/D_H increases; when S_g/D_H≤2, the stress superposition effect of soil between piles is significant, which is easy to lead to the damage of the interface of helical pile core-cement soil column, but when C_ref/S_u≥40, the damage mode will not be changed again, and it is shown as the damage of the interface of cement soil column-soil.