Study On Prediction Of Water Inflow Into Shuang Bei Tunnel And Operation Early Warning Measures

With the development of transpiration infrastructure in the southwest region, the tnnel engineering was getting larger and larger. In the process of tunnel construction, water inrush,large deformation of soft rock and rock burst disasters had occurred because of complex geological conditions. The water inrush that caused casualties and economic loss in all kinds of geological disasters was the most serious. Not only it can lead to heavy casualties or serious delay, but also irreversible pollution and ecological destruction for water resources and environments of the ground surface and tunnel site area. And in the operation stage, tunnel gushing happened because of the close contact between underground water of the Karst area and rainfall that caused the harm to the driving safety.The paper predicted the water inflow of construction and operation and put forward the precautionary measures at the example of Chongqing Shuangbei tunnel. The main research contents and results were as follows:(1) The factors of tunnel inflow were evaluated according to geological condition and hydrological condition of tunnel site area, and the ground water model that applied in zhong Liangshan Guanyin gorge area and taking account the equivalent medium model of fracture was put forward on the basis of the seepage theory.(2) The groundwater dynamic was divided and the water inflow of each segments was predicted with the theoretical formula. Compared the results with the actual monitoring data, the normal and the maximum discharge formula of each tunnel sections was determined.(3) The hydrogeological conceptual model was established through the infinite difference software Visual MODFLOW, and was used to forecast the average water inflow of each sections. It demonstrated the applicability of the software and the seepage field of tunnel area under construction stage was studied.(4) The gushing water in dry season and rainfall during the operation stage were predicted, and the early warning measures were proposed.