Dynamic impedances of pile groups with embedded caps in homogeneous elastic soils using CIFECM

Significant research has been reported on the dynamic analysis of pile groups. However, in most of the cases, the effect of pile cap is neglected despite the fact that there may be additional interactions due to the presence of the cap. This paper presents the dynamic impedances for the pile groups with caps embedded in isotropic homogeneous elastic soils. A general three-dimensional finite element procedure is developed. The system is sub-structured into bounded near-field and an unbounded far-field. The pile-soil system of the near-field is modeled using solid finite elements, and the unbounded elastic soil system of the far-field is modeled using the consistent infinitesimal finite element cell method (CIFECM) in the frequency domain.The method has shown excellent agreement with the published results for dynamic response of pile groups with a free-standing pile-cap. The dynamic impedances of pile groups with embedded cap are presented. Each pile group is capped with a thick pile-cap, embedded in the near-field soil domain. The dynamic impedances of 2×2 pile groups are presented, for different spacing of piles and thickness of the pile-cap with different embedment ratios. It was found that even for a small embedment ratio, the dynamic interactions due to cap can be significant.