软土地基28.4m深沉井不排水下沉法施工技术

Undrained Sinking Caisson Construction Technology of a 28.4m Deep Well in Soft Soils

为了实现某28.4m深沉井在深厚软土地层中下沉,对该大型沉井的制作、接高、下沉方案选择、不排水下沉法施工工艺等关键技术进行研究,并验算下沉系数和止沉系数。结果表明该沉井不排水下沉法施工工艺每个阶段的下沉系数均大于1.05,满足下沉需要。终沉阶段在下沉深度为13.9m处的止沉系数1.07大于1,处于不稳定状态,采取粗砂增阻法,增加井壁与土层之间的摩阻力,能降低止沉系数,确保施工顺利完成。

To construct a 28.4 m deep large caisson well in the soft soils,key technologies such as fabrication,section connection,sinking method selection,and undrained sinking construction technology are discussed in this paper.And the subsidence coefficient and anti-subsidence coefficient are calculated.The study shows that the subsidence coefficient of undrained sinking caisson construction method in each stage is greater than1.05 and meet the requirement of subsidence.When the final stage depth reaches 13.9 m,the anti-subsidence coefficient is 1.07,which is greater than 1 and indicates an unstable state.The coarse sand resistance increasing method is then applied to increase the friction between the well wall and the surrounding soils.This method reduces the anti-subsidence coefficient and ensures the smooth completion of the construction.