隔离桩对堆载下群桩下拉荷载的屏蔽效应

目前关于隔离桩对堆载下群桩负摩阻力及下拉荷载屏蔽效应的研究甚少,我国规范也未对隔离桩的设计参数给出建议。定义下拉荷载屏蔽效应系数这一概念；建立考虑桩-土作用的三维有限元模型,通过数值计算结果与模型试验数据的对比,验证数值模型的准确性。以群桩效应系数和下拉荷载屏蔽效应系数为评价指标,研究隔离桩对堆载下基桩负摩阻力与下拉荷载的屏蔽效果,分析隔离桩桩长、边长、与最外侧基桩间距3个因素对屏蔽效果的影响规律,对隔离桩的设置给出参考。研究成果可为堆载时群桩负摩阻力的消除及隔离桩的优化设计提供参考。

The Shielding Effect of Isolation Piles on the Dragload of Pile Group Under Surcharge load

There is still little research about the shielding effect of isolation piles on the negative skin friction (NSF) and dragload of pile group under surcharge load with the isolation piles outside. The national technical code also does not give advice on the design parameters of the isolation piles. In this paper, the concept of shielding effect coefficient on dragload is defined, then the three-dimensional finite element numerical analysis considering pile-soil interaction is established, and the accuracy of the numerical model is verified by comparing the numerical calculation results with the model test data. Taking the pile group effect coefficient and the shielding effect coefficient for dragload as evaluation indexes, the shielding effect of isolation piles on the NSF and dragload of pile group under surcharge load is studied, the influence of the three parameters such as the isolation pile length, the isolation pile side length as well as the distance between the outermost foundation pile and isolation pile is researched, and suggestions are also given for the setting of isolation piles. The research results can provide references for the elimination of the NSF of pile group and the optimization design of the isolation pile under surcharge load.