上海滨江软土地区深基坑工程变形特性实测分析

Monitoring Analysis of Deep Excavation in Shanghai Soft Soil Near a River

上海某变电站深基坑工程位于滨江软土地区,为了确保工程施工的顺利开展,基坑开挖施工期间进行了全面监测。监测内容包括坑外承压水水位、围护结构侧移、围护结构外侧土体侧移、围护结构顶部竖向位移、立柱回弹以及支撑轴力。监测数据表明:采用早强混凝土可能会引起较大的围护结构侧向位移;围护结构的侧向位移随开挖深度增大而增大,最大侧移深度随开挖深度增大而下移,均处于开挖面的附近;围护结构外侧土体的侧向变形发展规律与围护结构基本一致,且外侧土体的侧移均小于其对应围护结构的侧移;而底板的整体浇筑和地下结构施工对基坑变形有很好的限制作用。

A deep foundation pit is located in Shanghai soft soil near a river. In order to ensure construction going smoothly, a systematic monitoring was carried out during the whole process of excavation. The measured excavation responses included water level of artesian water, retaining structure deflection, lateral displacement of soil behind retaining structure, the vertical displacement of retaining structure top, uplifts of interior steel columns and axial forces of propping struts. Based on the analysis of field data, the following major findings were obtained ： the early strength concrete strongly affects lateral displacement of retaining structure ; The lateral displacement of retaining structure increases along with the excavation depth, the maximum lateral displacement depth moves down with the increase of excavation depth, which is close to the excavation face; the lateral deformation law of development of soil behind the retaining structure is basically identical with the retaining structure, and the lateral displacement of the outside soil is less than its corresponding displacement of retaining structure. The construction of base slab and understructure helps to stabilize the soil-structure system by suppressing the vertical movements of the retaining structure and interior steel column.