砂卵石地层深基坑监控量测与数值模拟分析

Monitoring Measurement and Numerical Simulation Analysis of a Deep Foundation Pit in the Sand-Gravel Layer

以成都某轨道交通砂卵石层深基坑为研究对象,对基坑开挖过程中桩身水平位移、周边地表沉降和内撑轴力进行监控量测,并采用midas GTS三维有限元软件进行模拟分析。结果表明:地铁车站深基坑的变形具有明显的空间分布特征,坑角效应显著;基坑扩大端围护桩的水平位移和周边地表沉降均小于标准段;桩身水平位移、地表沉降及内撑轴力的模拟值与实测值相近,有限元分析可较好地预测开挖过程中基坑的应力与变形演化规律;桩顶水平位移的实测值远大于计算值,可能与土体本构模型、基坑周边荷载及施工工序与实际不符等有关。

Taking the deep foundation pit in the sand-gravel layer at a station of Chengdu Metro Line 30 as the research object,the horizontal displacement of the pile shaft,the surrounding ground surface settlement,and the axial force of the inner support during the excavation of the foundation pit were monitored and measured,and the simulation analysis was carried out by using the midas GTS three-dimensional finite element software.The results showed that the deformation of the deep foundation pit at the subway station has obvious spatial distribution characteristics,and the pit angle effect is significant.The horizontal displacement of the retaining pile at the expanded end of the foundation pit and the surrounding ground surface settlement are smaller than those at the standard section.The simulated values of the horizontal displacement of the pile shaft,the ground surface settlement,and the axial force of the inner support are close to their measured values,indicating that the finite element analysis can better predict the stress and deformation evolution law of the foundation pit during the excavation process.The measured value of the horizontal displacement of the pile top is much greater than the calculated value,which may be related to the inconsistency between the soil constitutive model,the load around the foundation pit and the construction process with the actual situation.