砂土地基中开挖过程对立柱桩的影响分析

INFLUENCE OF EXCAVATION PROCESS IN SAND ON ERECT COLUMN PILES

立柱桩对基坑工程的稳定性有重要影响.基于快速拉格朗日法(fast Lagrangian analysis of continua-3D,FLAC3D),考虑桩土之间的相对滑移作用,深入分析了砂土地基中开挖条件下不同布桩方式对立柱桩桩身拉力、最大拉力位置及桩顶回弹量等的影响.结果表明:开挖对立柱桩的影响有明显的空间效应,开挖对中心桩的影响最大,角桩最小;开挖使立柱桩桩身内产生了拉力,群桩基础内的中心桩最大拉力值大于单桩的最大拉力值,且最大拉力值位置随桩数的增加而上移,并最终稳定在0.5倍的有效桩长;中心桩桩顶回弹量先随着桩数的增加而增大,然后当桩数增加到一定的数量后减小.

The erect column piles have an important effect on the stability of the foundation pit. Based on the three-dimensional explicit finite-difference program, this paper analyzes the impact of the tension force, the location of the maximum tension force and the heave of piles on the column piles with consideration of the interruption between soil and piles. It is shown that the influence of the excavation on the erect column piles has an obvious spatial characteristic, with the maximum influence on the center pile and the minimum on the corner pile. The tension force is induced by excavation, the location of the maximum value moves upward of the column pile, and finally stops at half of the effective insertion depth of pile foundation, the maximum tension force of the center pile in pile group is larger than that of a single pile; the heave of the pile top increases with the numbers of piles, and then decreases when the pile number is increased to a certain value.