兰州地铁某车站深基坑开挖变形特性分析

Deformation characteristics of excavation of deep foundation pit at a metro station in Lanzhou

对兰州市某地铁站深基坑桩顶水平位移、桩体水平位移和地表沉降变形进行跟踪监测,分析其变化规律。监测结果表明:桩顶水平位移随基坑开挖逐渐增大,靠近内支撑的桩顶水平位移变化较平缓;桩体水平位移随着深度增加呈现先快后慢、先陡后缓的变化趋势,距桩顶2/3处会出现水平位移最大值;距离基坑越近地表沉降量越大,变化速率越快。最后借助有限元软件Geostudio对基坑开挖进行了模拟,并将数值模拟结果与监测结果进行了对比分析,结果表明,数值模拟和监测结果较为接近,变化规律基本一致,证明了设计方案和有限元模型的可靠性,可为今后类似工程的设计和施工提供很好的借鉴意义。

The horizontal displacement of the pile top, the horizontal displacement of the pile and the settlement of the ground surface in the deep foundation pit of a subway station in Lanzhou are monitored and analyzed. The results show that the horizontal displacement of pile top increases with the excavation of the foundation pit, and that of the pile tip close to the inner support is relatively smooth. With the increase of depth, the horizontal displacement of the pile presents the trend of 'being first fast and then slow, first steep and then slow,' and there will be a maximum value at 2/3 points from the top of the pile. The more the ground settlement is, the faster the change rate is. Finally, the finite element software Geostudio is used to simulate the excavation of the foundation pit, and the numerical simulation results are compared with the monitoring ones. It is indicated that the results of numerical simulation and monitoring are close, and the law of change is basically the same. The reliability of the design scheme and finite element model is proved. It can provide a good reference for the design and construction of similar projects in the future.