| Chongqing,the only municipality directly under the central government in southwest China,plays an important strategic pivot for the development of the western region at the national strategic level,also an important link between the“Belt and Road”and the Yangtze River Economic Belt,as well as an important role for the inland open highland.The Tunnel excavation in zhongliang mountain area is accompanied by secondary geological disasters such as tunnel water gushing and groundwater leakage,which brings adverse effects on construction safety and people's production and life.In the vicinity of the Xiema Tunnel,many water level and water consumption monitoring points were set up.When the tunnel water inflow and rainfall changed,these monitoring points showed different degrees of response,and the groundwater dynamic change process was studied and calculated based on this.The parameters of karst aquifer in the block structure area are effective means and important ways to reveal and understand the hydrological change process,and can also provide reference for hydrogeological research under similar conditions in the future.On the basis of fully demonstrating the hydrogeological conditions of the tunnel area of the Xiema Tunnel,the rainfall,tunnel water inflow and area were analyzed with different types of monitoring data such as rainfall,tunnel water inflow,drilling water level,flat flow and surface water level.Correlation and response time of groundwater dynamics.Aiming at the significant water inrush process in the groundwater level,the hydrogeological parameters of the aquifer were calculated by dynamic analysis method,including the permeability coefficient K and the water storage rate u,and the three-dimensional numerical model and typical profile model of the groundwater flow were further established.Inversion and optimization were carried out.The main research results of the thesis are as follows:(1)The two wings of the Guanyinxia anticline and the core are relatively separated from each other.The hydraulic connection between the karst aquifers in the east and west troughs is weak.The groundwater is mainly recharged by atmospheric rainfall,and is discharged from the south to the north to the Jialing River.There is a strong positive correlation between groundwater dynamics and rainfall in the study area,and the increase of tunnel water inflow is negatively correlated with groundwater level.(2)The SPSS correlation analysis of each data and the analysis of the spatial position of the monitoring points show that the correlation between the monitoring points and the rainfall is positively correlated with the elevation of the monitoring points.The higher the elevation of the monitoring points,the rain and rainfall The positive correlation of quantity is also more significant.With the decrease of monitoring point elevation,the tunnel water inflow gradually becomes the main factor affecting the dynamic characteristics of groundwater in the study area.(3)By analyzing the different lag time of the monitoring points on the rainfall and the amount of water inflow from the tunnel,it is found that the closer the karst trough is to the east of the Guanyinxia slant east and the west trough,the faster the response to the gushing water in the tunnel.This may be due to the existence of groundwater-preferred water-conducting channels near the lithologic boundary between the Guanyinxia slanting east and west troughs.The lag time of rainfall at the monitoring point also shows a spatial lag characteristic that gradually increases from south to north.The monitoring point farther away from the tunnel has a longer response time to the tunnel water inflow.Therefore,the longer the distance from the tunnel plane,the longer the response time of the monitoring point to the tunnel water inrush.Using the water balance correlation formula,it is concluded that the value of the west trough is 0.006,and that of the east trough is 0.005.(4)By analyzing and analyzing the water inrush event of the Xiema Tunnel in April 2015,it is concluded that under the homogenization condition,the West Valley aquifer parameter K=0.34 E-01(m~3/d),u=0.5 E-02;East trough aquifer parameter K=0.1 E-01(m~3/d),u=0.3 E-02.By establishing a three-dimensional groundwater flow numerical model for the study area,the file is exported to USGS-ModelMate for parameter inversion,and the hydrogeological parameters of the West Valley are K=0.8643 E-01(m~3/d),Ss=0.6507 E-04.East trough K=0.3773 E-01(m~3/d),Ss=0.2969 E-04.According to the aquifer and parameter drilling data,it is speculated that the karst development degree of the west valley of Guanyinxia may be even worse than that of the eastern trough. |
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