In this paper, the lateral limiting pressure offered by the deep ‘flow-around’ soil failure mechanism for perimeter (ring) pile groups in undrained soil is explored using two-dimensional finite-element (FE) modelling. A parametric study investigates the role of group configuration, pile–soil adhesion, group size, pile spacing and load direction on group capacity and corresponding soil failure mechanisms. The FE output shows that the plan group configuration (square or circular) has a negligible influence on lateral capacity for closely spaced perimeter pile groups. When compared to ‘full’ square pile groups with the same number of piles, the present results suggest that for practical pile spacing (≳ two pile diameters), perimeter groups do not necessarily increase capacity efficiency, particularly if the piles are smooth. Nevertheless, perimeter groups are shown to be characterised by both the invariance of their capacity to the direction of loading and their highly uniform load-sharing between piles, which are beneficial features to optimise design.

中文翻译：

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围桩群深部土体破坏机理数值分析

在本文中，使用二维有限元 (FE) 建模探讨了不排水土壤中周边（环形）桩群的深层“流动”土壤破坏机制提供的横向限制压力。参数研究调查了组配置、桩土粘附、组大小、桩间距和荷载方向对组容量和相应的土壤破坏机制的作用。有限元输出表明，平面组配置（方形或圆形）对紧密间隔的周边桩组的横向承载力的影响可以忽略不计。与具有相同桩数的“完整”方形桩组相比，目前的结果表明，对于实际桩间距（≳ 两个桩直径），周长组不一定会提高容量效率，特别是如果桩是光滑的。尽管如此，