紧邻基坑群坑开挖相互影响三维数值模拟

Three-dimensional Numerical Simulation on Interaction among the Adjacent Group Excavation

随着城市化的发展,基坑施工条件日趋复杂,特别是基坑群开挖面临着复杂的相互影响问题。本文以国内某基坑群工程为例,基于小应变硬化土(HSS)模型,采用三维数值模型对基坑群的开挖进行模拟,并结合实测数据对基坑群开挖的相互影响进行了分析。结果表明:数值模拟计算结果与实测结果趋势基本吻合,说明HSS模型适用于基坑工程的数值分析;随着相邻基坑的开挖,后开挖基坑会引起已开挖基坑周边土体产生附加沉降、支护结构产生附加变形;对于已开挖至坑底的基坑,邻近基坑的开挖相当于坑外卸土,会引起先挖开基坑的支护结构产生向后开挖基坑方向的附加侧向变形。因此,群坑基坑设计中,考虑群坑之间的相互影响是必要的。

With the development of urbanization,the construction conditions of foundation pits are becoming more and more complex,especially group excavation meets complex interaction problems among various projects.Taking the group excavation projects in Guangzhou as an engineering case,the excavation sequences of the foundation pits are simulated using a three-dimensional numerical model based on hardening soil-small strain model,and the results are compared with the measured data to analysis the interaction of group excavation.The results show that the lateral displacement of numerical simulation results are basically consistent with the measured results,indicating that the hardening soil-small strain model is suitable for the numerical analysis of foundation pit projects;with the excavation of adjacent foundation pits,the additional ground settlement and the additional lateral displacement of supporting structure of the existing excavation caused by follow-up foundation pit;for the existing foundation pit,the excavation of the adjacent foundation pit is equivalent to unloading outside the pit,and the supporting structure of the existing foundation pit will appear as lateral deformation in the direction of the follow-up foundation pit.Therefore,it is necessary to consider the interaction in the design of group excavation for the similar projects.