考虑开挖全过程的基坑坑外任意地表沉降实用计算方法

Practical calculation method of arbitrary ground surface settlement outside basement considering the whole process of excavation

基于所收集的16个杭州地铁基坑案例,首先,建立基坑相对“标准化模型”,包括基坑物理参数模型、基坑施工过程模型以及场地土层参数模型,并由此进行三维有限元建模分析;其次,将建模计算的地表沉降值与工程实测、既有文献解进行对比,验证所建标准化模型的准确性,并提出考虑全开挖过程的杭州地铁车站基坑坑外任意地表沉降实用计算方法;最后,分析杭州地铁基坑各开挖阶段地表沉降特征。研究结果表明:当开挖深度超过7 m时,坑外地表横向沉降曲线由“悬臂状”转化为“三段式”折线;随挖深的增加,地表沉降显著增大,地表最大沉降的位置距基坑距离也逐渐增大。所建标准化模型和所提实用计算方法具有准确性。

Based on the collected 16 cases of Hangzhou metro basement,the relative "standardized model" of basement was firstly established,including the physical parameters of basement,excavation process and soil distribution,and the three-dimensional finite element modeling analysis was carried out.By comparing the ground surface settlement obtained from the numerical model with the measured data as well as the existing solutions from the published literature,the accuracy of the numerical model was verified.Subsequently,a practical calculation method considering the dynamic excavation was proposed to predict the transverse and longitudinal ground surface settlement outside excavation.Finally,the deformation characteristics of ground surface settlement during each stage could be furthely analyzed.The results show that when the excavation depth exceeds 7 m,the transverse ground surface settlement outside the excavation is transforms from "cantilever" to "three-stage" broken line distribution.With the increase of excavation depth,the transverse ground surface settlement and its transverse distance to excavation increase significantly.The proposed model and method are both accurate.