组合围护形式在软土地区坞口基坑中的应用

坞口基坑具有临江的地理特点，传统方案采用统一的钻孔灌注桩围护形式，不能很好满足后续拆除以及船舶下水的特殊使用需求。依托上海软土地区某坞口基坑工程，提出钢板桩+灌注桩组合的围护形式，临江侧采用钢板桩，发挥其易于施工和拆除的特点，其余3侧采用钻孔灌注桩，保证围护结构的整体刚度，搭配止水帷幕和支撑体系在施工过程中共同发挥作用。现场实施结果表明，在钢板桩和灌注桩的组合围护下，坞口基坑的变形和支撑受力均得到有效控制，验证了组合围护形式在工程应用中的可行性，可为船坞基坑工程的设计施工提供参考。

Application of compound retaining system in dock entrance foundation pit in soft deposit

Dock entrance foundation pit is usually by the water,and the uniform retaining structure like bored pile is often used in conventional engineering,which does not meet the special needs of subsequent dismantling and ship launching.In this paper,a compound retaining system of steel sheet pile and bored pile is proposed based on a rectangular foundation pit of a dock entrance in Shanghai soft deposit.The excavation is retained by steel sheet pile at riverside which is advantageous in construction and dismantling and bored pile at the other 3 sides which is stiff in retaining.The retaining structure,the waterproof curtain and the supporting system play a joint role in the construction process.The field construction shows that the deformation and force of the dock entrance foundation pit retained by a combination of steel sheet pile and bored pile are both effectively controlled,which verifies the feasibility of the compound retaining system in engineering application,and can provide reference for the design and construction of the dock entrance foundation pit.