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以深圳某深大基坑工程为背景,运用大型有限元软件,建立了基坑开挖支护三维有限元计算模型。分析了复杂环境下新建基坑土层与支护结构变形规律及紧邻既有基坑变形特性,且与实测结果进行了对比分析。研究结果表明:既有基坑的位移增量随着新建基坑开挖尺寸的增大而增加,故深基坑开挖过程中每一步开挖尺寸变化不宜过大,以防引起既有建筑物位移的显著变化。靠近既有基坑一侧土压力相对更小,新建基坑开挖应力释放引起的围护结构向临空面移动效应得到弱化,该区域土层位移减小。与实测结果对比分析表明,数值计算模型具备合理性。
Taking a deep foundation pit project in Shenzhen as a background, a three-dimensional finite element model of excavation and excavation of a foundation pit is established by using the large-scale finite element software. The deformation of the newly built foundation pit and supporting structure under complex environment and the deformation characteristics of the existing foundation pit are analyzed, and the results are compared with the measured results. The results show that the incremental increment of the existing foundation pit increases with the excavation size of the new foundation pit, so the excavation of the deep foundation pit should not be oversized at every step of excavation in order to prevent the existing building Significant changes in material displacement. The earth pressure on the side close to the existing foundation pit is relatively smaller. The movement effect of the envelope to the free surface caused by the stress of excavation of new foundation pit is weakened, and the displacement of soil layer in this area is reduced. The comparison with the measured results shows that the numerical calculation model is reasonable.