基于FLAC^(3D)的桩锚支护结构变形分析

Deformation Analysis of the Pile-anchor Retaining Structure Based on FLAC^(3D)

以郑州某深基坑工程为研究背景,介绍了工程概况与支护设计方案,并对基坑支护系统变形的现场监测结果进行了分析,重点研究了施工过程中深层水平位移随开挖深度和时间的演化规律。利用FLAC3D有限差分软件对基坑北侧桩锚支护段开挖和支护进行三维数值仿真模拟,计算基坑开挖过程中基坑侧向位移,将所得计算结果与现场监测结果对比,再改变支护设计探究影响基坑变形的敏感性因素。结果表明:基坑施工严格执行"边开挖边支护"原则,桩锚支护系统能有效限制支护系统的侧向变形,FLAC3D数值模拟结果与监测结果基本一致,数值模拟结果是可信的。锚索预应力的大小对限制支护系统的侧向位移有重要作用,支护桩合理的入土深度能够减缓基坑侧向变形。

Based on a deep foundation pit in Zhengzhou,the geological conditions of the engineering site and support structure design were introduced. Meanwhile the monitoring data of the supporting structure deformation for the foundation pit were analyzed,and the developing law of the deep horizontal displacement that changed with the depth and duration of excavation in the process of construction was emphatically studied. The excavation and supporting of the pile-anchor supporting section in the north of foundation pit were simulated by adopting the finite difference software FLAC3 D,through which the lateral displacement of foundation pit during excavation was calculated,and then compared with the monitoring data. In addition,the design of the supporting structure was altered to search for the sensitivity factors that caused the deformation. The results indicate that pile-anchor supporting system can effectively protect the supporting system from deformation if the rule of ＂excavation and protection should be simultaneous＂during the construction of the foundation pit is carried out strictly,the results of numerical simulation by FLAC3 Dare basically the same with the monitoring data,thus the simulation results of the former can be trusted; the magnitude of the anchor cable prestress plays an important role at preventing the lateral displacement of the supporting structure; the reasonable embedded depth of the supporting piles can also mitigate lateral deformation of foundation pits.