Hazard of water gushing caused by Nanshan Tunnel engineering, Chongqing

In this paper, the radius and inflow of water gushing are respectively analysed, by using the methods of groundwater dynamics, Goodman experiential formula and experiential analysis formula. In addition, inflow rate of the water affected by railway tunnel constructions is also comparatively analysed. The analytical results enable us to draw the conclusions as follows: (1) the radius (642m in length) of the gushing water at Nanshan tunnel is smaller than that at light rail tunnel (727m in length). The altitude of the light rail tunnel is lower than that of Nanshan tunnel, which intercepts some of water-bearing area and decreases the quantity of water flowing into Nanshan tunnel. (2) The inflow of the gushing water estimated by Coase Peskov method is much closer to the figures from field measurements. (3)The influence of water leakage at the Tushan lake is much smaller than that at the small lake, as the inspective result gained from the water leakage of Zhongliang Mountain. Tushan lake is located within the influence range of Nanshan tunnel, which is affected by Nanshan tunnel. There is a comparatively larger lake and smaller one in the Tushan lake area. The larger lake which has been formed in a quite long period of time, resulting in a thick layer of silty sediment at the bottom of the lake; and it is lightly affected by water leakage of the tunnel. On the contrary, the smaller one of Tushan lake, with a thin layer of sediment at its bottom, is greatly affected by the water leakage of the Nanshan tunnel. The karst collapse hazard within the influence range of Nanshan tunnel deserves attentions, because water leakage of the tunnel may lead to the loss of buoyant force of the rock mass. In addition, to minimize any losses due to the hazard, it is important for the public to involve in monitoring and mobilizing.