淤泥层深基坑开挖及降排水施工方法

Construction Method of Deep Foundation Pit Excavation and Dewatering in Silt Layer

基坑开挖的方法、机械选型、降排水方案以及后续工序的衔接直接影响着工程施工的整体进度。深圳市某水质净化厂某结构单体下卧地质主要为第四系海相沉积层,主要土质为淤泥,最大开挖深度约7 m;且受外部影响,开挖工作在临近结构主体施工完成后开始。以该构筑物为例,对淤泥层深基坑开挖、设备选型及降排水施工的原则与方法进行研究。结合工程实际,选定分层分块开挖与盆式开挖相结合的开挖方式,“长短结合、大小相适”的机械选用原则与“深干沟、强排水”的经常性排水原则开展施工。

The method of foundation pit excavation,mechanical selection,dewatering and drainage scheme and the connection of subsequent processes directly affect the overall progress of engineering construction. The underlying geology of a single structure of a water purification plant in Shenzhen is mainly quaternary marine sedimentary layer,the main soil is silt,and the maximum excavation depth is more than 7m;due to external influence,the excavation work starts after the completion of the main construction of the adjacent structure.Taking the structure as an example,this paper studies the principles and methods of deep foundation pit excavation,equipment selection and drainage construction in silt layer. Combined with the actual situation of the project,the excavation method of combining layered and block excavation with basin excavation is selected,and the mechanical selection principle of “combination of length and size” and the regular drainage principle of “deep trunk ditch and strong drainage” are selected for construction.