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

Abstract:

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.

Key words:under-river shield tunnel; kick; pumping test; well dewatering