管井降水技术在江底取水隧道修复中的应用

Tube well dewatering technology for repair of the water intake tunnel under the Yangtze River

苏南某电厂江底取水隧道在掘进时发生沼气喷溢引起承压水携带泥沙涌入,隧道修复过程中需要防止承压水再次突涌,而能否通过管井降低长江水体下巨厚的承压含水层水位引起了巨大的争议。本文结合水文地质条件分析及现场抽水试验,查明目的含水层与江水及下部巨厚承压含水层之间的水力联系,得到了各层的水文地质参数,提供了可靠的降水方案,并对沉降变形进行了预测分析,解决了水上降水管井施工等一系列难题,对类似工程具有重要的借鉴意义。

In the process of shield excavation of the water intake tunnel for a power plant in the south of Jiangsu,the confined water flooded the tunnel with sediments due to a gas kick.It was necessary to prevent the confined water from surging out again during the tunnel repair.Whether the water level of the massive confined aquifer under the Yangtze River can be reduced by the tube well caused a great controvesy.Base on the analysis of hydrogeological conditions and field pumping tests,the hydraulic connection between the objective aquifer with the river water and the lower massive confined aquifer was found,the hydrogeological parameters of each layer was calculated,a reliable dewatering scheme was provided,and the subsidence deformation was predicted and analyzed.It also has solved a series of difficult problems such as the construction of pipe wells over water,providng important reference of similar projects.