Study On The Groundwater Environmental Effects Caused By Construction Of Neighboring Tunnels In Zhongliang Mountain Area Of Chongqing

Chongqing City as the largest municipality directly under the central government,which is the developed economy city.in the southwest of China.The northwest and central Chongqing is mainly low hills and hills in terrain.Southeastern of the city neighboring Daba,Wuling Mountain,it is a city called "mountain city" as its undulating terrain.Urban and adjacent economic circle was cut off by the ridge,formed a great obstacle to the regional economic integration.In this study,Zhongliang Mountain is located in the west of Chongqing city,which were cut by the Yangtze River and Jialing River at north and south.With the development of economic needs and the level of engineering and technology,the study area have built a large number of tunnel to increase its traffic convenience in the last three decades.Howere,The construction of the tunnel project has produced a series of groundwater environmental geological problems.Especially the construction of the tunnel meet the underground river conduit or the fault often cause gushing water at the excavating face,Resulting in particularly serious engineering accidents.This paper analyzes the construction condition of tunnel in the Zhongliang Mountain block between two rivers,puts forward the problem of the groundwater environmental effect under the construction of the neighboring Tunnels.Based on the unique geological conditions of the Guanying gorge anticline to discussed the influence of the construction of the neighboring tunnel on the groundwater environment.After analyzing the characteristics of existing tunnels' effects of groundwater environmental in Zhongliang mountain area,Selectting the Xiema tunnel which in the south of the Guidao 6th line tunnel as a numerical simulation object Analysis the groundwater environmental effect caused by construction of neighboring tunnels in Zhongliang mountain Area.And get the following conclusion:1.The main structure of the study area is Guanying gorge anticline,the east and west sides of the valley and the middle of the peak cluster monadnock exposed stratum of Feixianguan Group(T1f),Jialingjiang Group(T1j)and Leikoupo Group(T2l).Feixianguan Group four segment(T1f4)is an non-karst strata,which blocks the groundwater contact between the core part and two sides' Jialingjiang Group and the Leikepo Group strata.The water blocking effect of the Jurassic strata in the two wings makes the karst water in the anticline become self-contained system.According to the analysis,the groundwater in the Guanyin gorge anticline is mainly composed of shallow circulation,and the regional deep recirculation of groundwater is slower.2.The influence of tunnel construction on the groundwater environment is mainly to change the structure of the regional aquifer,it is controlled by different influencing factors.The construction of the neighboring tunnel in the study area is extensive,and the groundwater environmental effect is different from single tunnel,and the environmental effect of the groundwater caused by the different forms of the adjacent tunnel is different.3.The construction of neighboring tunnel in Zhongliang mountain leads to the aquifer's drain,karst collapse and destruction of geothermal resources,and the distribution of groundwater environment negative effects of various types has obvious stratigraphic zonation.The number of dry spring in the karst area is significantly higher than in the non-karst area.On the other hand,the proportion of dry spring in the karst area is higher than that in the non-karst area,and the karst collapse is the most developed in the Jialingjiang Group strata.4.Selecting the typical neighboring tunnel construction in the study area to simulate the four types of working conditions,namely the natural state seepage field,the seepage field after the old tunnel construction,the seepage field under the unlined tunnel and the seepage field after the new tunnel lining The analysis shows that the spatial relationship of the neighboring tunnel,the lithologic relationship of the stratum,the tunnel condition and the atmospheric precipitation are closely related to the effect of the tunnel to the groundwater environmental.The simulation model prediction of the two-wing trough interception profile shows that the groundwater level in the two wings trough is different,and the cone of depression in the two wings trough section is also different.The eastern trough's recovery time is longer than the west trough,which is related to the development of underground karst and the karst form in the surface.