微型桩支护作用下的深基坑开挖过程力学响应分析

Mechanical Response of Deep Foundation Pit Excavation by Micropile Supporting

借助ABAQUS分析软件建立深基坑微型桩支护体系三维有限元模型,对开挖卸荷过程中微型桩的力学响应进行分析,探究由于开挖卸荷引起的体系应力、变形变化规律.分析结果表明,在基坑开挖卸荷过程中,当开挖到一定深度时,锚固段以上土体应力渐趋于零,而锚固段以下土体应力逐渐呈梯形分布;开挖过程中桩身承受正反弯矩,正弯矩逐渐增大,负弯矩则先增大后减小,锚固段可能出现走滑的现象;开挖结束后,桩身在靠近基坑底面处产生局部的倒"S"形扭曲变形,桩体呈双点拉剪破坏.

The three-dimensional finite element model of micro-pile supporting system for deep foundation pit was established by ABAQUS software. The mechanical response of the micro-piles was analyzed to explore the stress and deformation of the system which was caused by excavation unloading. The results showed that in the process of foundation excavation unloading, when it was excavated to a certain depth, the anchorage section above the soil stress was gradually trended to zero, and in the embedded section below the soil stress was gradually trended to trapezoidal distribution. During the excavation, the pile body was subjected to positive and negative moment. The positive bending moment was tended to increase, but the negative moment was increased and then shrunken. And the slip of the pile was appeared in the embedded section. After the end of digging, the micro-pile body had a local of S which was shaped the distortions near the bottom of the pit, and the pile had the double-point shear failure.