Prediction And Evaluation Of Water On The2nd Tunnel Of Tiefeng Hill,Wankai Highway

The2nd tunnel of Tiefeng hill is an important part of Wankai highway project, located in the territory of Chongqing Wanzhou District, across the Tiefeng hill mountain, the tunnel is about6km, the maximum depth is about750m, the tunnel site for a major geological structure back Tiefeng hill ramps, the tunnel is the first long tunnel which railway across the buried anticline Tiefeng hill. Anticline axis for the carbonate rocks, clastic rocks were holding the two wings, with tight anticlines, structural characteristics of closed storage. Tunnel engineering geology site area is very complicated hydro-geological conditions, the main engineering geological problems of Karst water gushing against the tunnel.In this paper, a large number of ground-based means of geological survey, drilling, engineering geophysics, hydrological and other engineering measures test,it reveals the law of the site area and the control of Karst development factors, the characteristics and the law of groundwater development.The controlling factors of Karst tunnel site area:geological structure, Karst hydrodynamic model of water, soluble carbonate rocks, terrain, topography and boundary conditions, and so on. The laws of Karst tunnel site area are:positive level, and bedding, and non-uniformity of the deep and vertical zonation, and so on.Groundwater type tunnel sites are mainly Quaternary pore water, bedrock fissure water and Karst water, the greatest impact on the tunnel is the Karst water, Karst water with "filled-type supply, runoff flow, and concentrate discharge" characteristics. Hydrodynamic vertical Karst can be divided into:epi-Karst zone, vadose zone, the season alternating with shallow saturated zone, the pressure of saturated zone and deep water flow with ease; Karst hydrodynamic level can be divided into:recharge areas, recharge of runoff areas and discharge areas. Tunnel site area of Karst water system is divided into shallow and deep Karst systems, shallow Karst system in the tunnel site is divided into South East anticline, anticlinal anticline axis and the North West Department of Karst water systems.According to the tunnel site characteristics of groundwater systems, we can predict water yield of the tunnel by groundwater runoff modulus method, and judge that the tunnel in Karst area may appears of large water oozing. The result is17537m3/d,18837m3/d and19023m3/d using groundwater runoff modules method, infiltration of precipitation method, and groundwater dynamics method. Also, the water inflow of the tunnel is predicted by subsection with the method of groundwater dynamics. Area under the tunnel site hydro-geological characteristics of Karst law, construction conditions, lithology, topography and other factors and results of Water, a comprehensive analysis and forecast of the tunnel sections focus on the location and gushing gushing manner and with the tunnel a long view of hydrological information were compared, using the traditional approach to the tunnel gushing forecast accuracy is relatively low, mainly due to the particularity of Karst area and the closure of the anticline with the characteristics of water storage structure, the impact of the tunnel are many factors gushing. Water oozing of the tunnel has many features:it mainly focuses on Karst area, the water inflow of southeast vane of anticline is more than northwest vane, the way of excretion of southeast vane of anticline is centrally water oozing and it is sporadic in northwest vane, central water oozing focuses on contact site of different lithology which is proved that the inhomogeneity of Karst and Karst water has the systematicness characteristic. Prediction and evaluation of the tunnel gushing on engineering, environmental impacts and hazards. According to the tunnel area of the project site hydrogeologic conditions, Water Tunnel proposed preventive measures. The influence to hydrology environment is evaluated after tunnel accomplished. The paper submits a tunnel gushing preventive measure:blocking mainly, advanced blocking and proper white-out. The number of3m3/m·d is suggested as the tunnel standard of discharge of water. Because of limiting discharge of water and lining wall rock, groundwater system recovers. It is also to ensure the construction, and reasonable to restore the ecological environment and to effectively curb the depletion of water resources.