Lateral Resistance Of Pile Group Research Articles

Evaluating the effect of pile spacing and configuration on the lateral resistance of pile groups

In this study, the effects of pile spacing and pile group (PG) configuration on the static lateral resistance of PGs are investigated using finite element (FE) numerical modeling. Three-dimensional FE models for a 4 × 4 vertical, battered, and mixed PG configurations were developed and analyzed at three pile spacings (3D, 5D, 7D) and for three clay soils (soft, medium, stiff). The nonlinear pile and soil behaviors were accounted for using elastoplastic constitutive models and a pile–soil interface model. The effects of pile spacing and configuration on the group efficiency, axial reaction in piles, and p-multipliers are discussed. The results showed that the battered PG had the largest group efficiency followed by mixed PG and then vertical PG at all pile spacings. The axial reaction in piles decreased only in two pile rows when the pile spacing increased in the three PGs. The back-calculated p-multipliers were different between the PGs with the largest values in the battered PG. Modifications to the p-multipliers used in practice are proposed to account for the effect of configuration in the battered and mixed PGs.

Group effect on ultimate lateral resistance of piles against uniform ground movement

In earthquake engineering, pile foundations are designed to withstand the lateral loading that results from large displacements due to ground movement caused by strong earthquakes. The distress and failure of superstructures occurs when the lateral load exceeds the ultimate lateral resistance of the piles. The aim of this study is to estimate the ultimate lateral resistance of piles especially in terms of the group effect induced by the pile arrangement. Several experimental and numerical analyses have been conducted on pile groups to investigate the group effect when the groups are subjected to uniform large horizontal ground movement. However, the ultimate lateral resistance of the pile groups in these studies was calculated by applying load to the piles. The present study directly assesses the ultimate lateral resistance of pile groups against ground movement by systematically varying the direction of the ground movement. Although the load bearing ratio of each pile in a pile group, defined as the ratio of the ultimate lateral resistance of each pile in a pile group to that of a single pile, is an important design criterion, it was difficult to assess in past works. This study focuses on the load bearing ratio of each pile against ground movement in various directions. The use of the finite element method (FEM) provides options for simulating the pile-soil system with complex pile arrangements by taking the complicated geometry of the problem into account. The ultimate lateral resistance is examined here for pile groups consisting of a 2 × 2 arrangement of four piles, as well as two piles, three piles, four piles, and an infinite number of piles arranged in a row through case studies in which the pile spacing is changed by applying the two-dimensional rigid plastic finite element method (RPFEM). The RPFEM was extended in this work to calculate not only the total ultimate lateral resistance of pile groups, but also the load bearing ratio of the piles in the group. The obtained results indicate that the load bearing ratio generally increases with an increase in pile spacing and converges to almost unity at a pile spacing ratio of 3.0 with respect to the pile diameter. Moreover, the group effect was further investigated by considering the failure mode of the ground around the piles.

Ultimate Lateral Resistance of Pile Groups in Sand

Experimental investigations on model pile groups of configuration 1 1, 2 1, 3 1, 2 2, and 3 2 for embedment length-to-diameter ratios Ld 12 and 38, spacing from 3 to 6 pile diameter, and pile frict...