大型基坑复合土钉支护结构的数值模拟与分析

Research on the Three Dimensional Numerical Simulation and Field Measurement Data of Composite Soil-nail Support in Large Foundation Pit

随着城市发展和建设,大型深基坑工程越来越多,受场地空间限制,在基坑设计与施工过程中,支护结构内力的变化、基坑周围地层的沉降以及周围环境的影响已成为评价基坑稳定的关键因素。本文基于FLAC3D软件,以邯郸天琴大厦深基坑工程为例,对该基坑复合钉支护结构进行了数值模拟,研究了复合土钉支护下边坡的变形与沉降、基坑开挖时塑性区的分布以及支护构件的力学特性变化规律。结果表明:土体的沉降影响范围和水平位移都与基坑开挖深度成一定的比例关系;通过基坑复合土钉支护结构的轴力与剪切变化特征分析,可推算出失稳区域的发生位置与形状。将数值模拟结果与实际监测数据进行对比分析,从而验证了模拟结果的可靠性,对基坑工程的设计与施工具有重要的参考价值。

With the development of cities,there are more and more large and deep foundation pits, but, due to the space limitation, the internal force variation of supporting structure, foundation settlement and its effect on the sur rounding environment are the key problems in the design and construction of foundation pits. Based on the differ ence algorithm of threedimensional display, FLAC3D has advantages in the simulation of mechanical properties, deformation and evolution of the plastic zone under the condition of the complex interaction of soil and supporting structure. This paper takes the foundation pit of Tianqin Bulling in Handan City as an example and analyzes the de formation and settlement of the slope supporting by the composite soilnailing, the distribution of the plastic zone in the pit excavation and the variation of the mechanical characteristics of support members. The results show that the influence scope of soil settlement and the horizontal displacement have certain relationship with excavation depth; meanwhile, the location and shape of potential slip side are figured out by analyzing the axial force and shear varia tion characteristics of the supporting structure. Through comparing simulation results with the actual measurement data, the paper verifies the reliability of the simulation which has significant reference for the design and construc tion of foundation pit engineering.