庆春路过江隧道基坑围护结构监测分析

Monitoring Analysis of Retaining Structures of Excavation Pit of Qingchun Road River-Crossing Tunnel in Hangzhou

摘要: 通过监测分析表明，在深基坑开挖过程中，围护体的最大水平位移与开挖深度和开挖时间密切相关，在多道支撑工况下，支撑轴力随开挖纵向长度增加、开挖深度增加呈波动变化，环境温度明显变化和强降雨等因素对支撑轴力的影响明显，邻近基坑的支撑架设与拆除对支撑轴力有较大影响，基坑周边地下水位变化是影响地表沉降的主因，及时架设支撑、尽快完成底板结构、减少基坑暴露时间在控制围护体位移的同时能有效控制地表沉降。工程实践表明，复杂地质条件下大型深基坑建设，建立两套相对独立的监测系统非常必要，有效的数据信息为建设者实时掌握结构工况、及时采取相应措施、顺利完成工程建设提供了重要保障。

Abstract: In situ monitoring demonstrates that the maximum horizontal displacements of the retaining structures are closely related to the excavation depth and time during excavation of the foundation pit. When multiple supports are applied, the axial forces of the supports fluctuate with increase of longitudinal length and depth of the excavation pit. Axial forces of the supports are significantly influenced by changes of external conditions such as temperature and rainfall. In addition, they are also greatly impacted by the set-up and removal of steel supports of the adjacent pit. The changes in ground water table resulting from dewatering and seepage are the main factors inducing settlement of ground surface. Displacements of the supports and the ground surface can be well controlled by in-time set-up of the supports, quick built-up of the basement and decreasing of stand-up duration. Field practice reveals that the implementation of two independent monitoring systems is essential during construction of large and deep excavation pits in complex ground conditions. Timely and effective monitoring gives a strong support to real-time acquirement of the conditions of the structures, in-time implementation of corresponding countermeasures and successful complement of the project.