高承压富水岩溶地层深基坑复合降水施工技术

Composite Dewatering Construction Technology of Deep Foundation Pit in High Pressure and Water Rich Karst Stratum

我国岩溶地区分布广泛,据不完全统计,我国广州、深圳、武汉、大连、无锡、贵阳、昆明、南宁等城市地铁不同程度穿越岩溶区,地下水位高,且具有承压性。在车站主体结构施工过程中,基坑降水效果的好坏对工程质量、安全、进度影响较大,目前国内深基坑降水一般采用井点降水和明抽,在透水性较好的土层中,降水效果好,但在高承压富水岩溶地层,由于岩石裂隙非常发育,大部分地下水存在岩溶裂隙中,水路的连通性存在较大的不确定性,井点位置无法精确定位于岩溶裂隙中,井点降水对于该地层的降水效果不佳。介绍了高承压富水岩溶地层中,结合排水暗沟的优点,通过复合降水施工技术达到降水的目的,确保主体结构施工处于无水工作环境,保证施工质量和安全,为类似工程提供施工经验。

China's karst areas are widely distributed.According to incomplete statistics,the subways in cities such as Guangzhou,Shenzhen,Wuhan,Dalian,Wuxi,Guiyang,Kunming,and Nanning pass through karst areas to varying degrees,with high groundwater levels and pressure.During the construction of the main structure of the station,the dewatering effect of the foundation pit has a greater impact on quality,safety,and progress of the project.At present,the dewatering of deep foundation pits in China generally adopts wellpoint dewatering and open drainage,which is in the soil with good water permeability.The precipitation effect is good,but in high-pressure water-rich karst formations,due to the very developed rock fissures,most of the groundwater exists in karst fissures.There is a large uncertainty in the connectivity of waterways,and the location of well points cannot be accurately determined in karst fissures.Among them,the well-point precipitation has a poor effect on the precipitation of this formation.In the high-pressure water-rich karst formation,combined with the advantages of drainage ditch,the composite precipitation construction technology is used to achieve the purpose of precipitation,to ensure that the main structure construction is in a water-free working environment,to ensure construction quality and safety,and to provide construction experience for similar projects.