| The municipality of Chongqing is a veritable ’mountain city’ with its valleys and75.33% of its land area covered by mountains.To keep pace with the rapid development of the city,an unprecedented number of tunnels have been constructed in Chongqing.The construction of tunnels has led to a series of environmental and geological problems,and a large part of the negative environmental effects are due to groundwater transport.In this thesis,we use the Huayan and Huafu tunnels in the Zhongliang Mountain region of Chongqing as the research object,and obtain detailed hydrogeological data through detailed field surveys.The analysis will provide a reference for subsequent research on the groundwater transport pattern of water-rich strata.The analysis has led to the following insights:1.A conceptual model of hydrogeology and a numerical model of groundwater transport for the rebuilt tunnel in water-rich strata,represented by the Huayan tunnel,was established,and the groundwater seepage fields of the initial state(no tunnel)and the Huafu tunnel only were simulated,which matched the measured data and verified the accuracy of the numerical model.2.The reinstated tunnel(Huayan Tunnel)has almost no impact on the groundwater environment around the Huafu Tunnel.There is no significant relationship between the groundwater level in the middle of the tunnel and the multi-year average rainfall,the tunnel length and the comprehensive hydraulic conductivity of the tunnel.Taking the tunnel operation for 5 years as an example,under the conditions of multi-year average rainfall of 800 mm,1200mm and 1600 mm,the influence of groundwater depth is 0.51 km,0.41 km and 0.26 km respectively;under the conditions of tunnel length of 1/2,1/2 and 2/3of the original length,the influence of groundwater depth is 0.41 km,0.43 km and 0.41km;under the condition that the tunnel integrated hydraulic conductivity is 0.02m/d,0.03m/d and 0.04m/d,the influence of groundwater depth is 0km,0.13 km and 0.30 km respectively.Overall,the extent of groundwater depth impact is negatively correlated with the multi-year average rainfall,largely independent of the tunnel length,and positively correlated with the tunnel integrated hydraulic conductivity.3.On the temporal scale,the difference in groundwater level within the tunnel’s landfall funnel decreases,with both the top width and depth decreasing with time.At the spatial scale,the difference in groundwater level within the central groundwater fall funnel is significantly smaller than the east and west sides,and the top width and depth are also significantly smaller than the east and west sides.4.Taking the top width of the precipitation funnel in the middle of the tunnel as an example when the tunnel has been in operation for 5 years,its value decreases from0.47 km to 0.24 km after the average rainfall for many years increases from 800 mm to1600mm;after the tunnel length increases from 1/3 original length to 2/3 original length,its value is 0.37km;and after the comprehensive hydraulic conductivity of the tunnel increases from 0.02m/d to 0.04m/d,its value increases from 0km to 0.27 km.Overall,with the increase of average rainfall for many years,the top width and depth of the groundwater landing funnel gradually decreased,the funnel tended to disappear,the groundwater around the tunnel was replenished,and the groundwater flowed into the tunnel from the area far away from the tunnel.With the increase of tunnel length,the width and depth of the top of the precipitation funnel gradually increased,and the groundwater near the tunnel continued to move to the area away from the tunnel.As the comprehensive hydraulic conductivity of the tunnel continues to increase,the width and depth of the precipitation funnel continue to increase,and groundwater near the tunnel continues to flow into other areas away from the tunnel. |
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