深基坑大尺寸物理模拟试验与基坑土体变形参数研究

Study on Soil Deformation Parameters Around Deep Pit by Large-Scale Physical Model Test

基坑工程中土体变形参数的研究对于基坑工程稳定性分析有重要的指示作用.本文基于相似理论的原理和方法,以中央电视台主楼基坑为试验对象,建立模型与实体基坑工程尺寸比例为1∶10的大型物理模型试验.对比物理模拟试验结果与实测资料发现:大型物理模型试验对于基坑开挖土体变形过程有更精确的模拟,其中模型桩顶最大水平位移约为开挖深度的0.32%,实际工况约为1.4%;模型被动土压力随开挖深度的变化规律与实际工况相似,且数值接近.物理模拟的结果与实际工况所检测的结果较为一致,可为实际基坑施工提供依据.

The study of soil deformation parameters in foundation pit engineering plays animportant role in the stability analysis of foundation pit engineering.Based on thetheory and method of similarity theory,this paper takes the pit of CCTV main buildingas the test object and establishes a large-scale physical model test in which the size ratioof the model to the real main building is 1∶10.Compared the physical simulation testresults with the real measured data,it shows that large-scale physical model tests havehigher accuracy in simulating soil deformation process excavated by foundation.Themeasurement of the maximum horizontal displacement of the model’s top is about0.32% of that of the excavation depth,and in the real condition the percentage is about1.4%.The trend of passive earth pressure changing with the excavation depth is similarto that of the actual working situations and the actual values of these two conditions areclose to each other.The results of the physical simulation are in good agreement with theresults obtained from actual conditions and can provide evidence for actual pit construction.