Study On The Influence And Evaluation Of Highway Tunnel Construction On The Negative Effects Of Groundwater Environment

In recent years,my country’s highway tunnel engineering construction has made significant progress and breakthroughs,but at the same time it has brought many negative effects to the groundwater environment,causing problems such as falling groundwater level,surface water depletion,surface subsidence and water pollution.This paper conducts related research on the impact and evaluation of the negative effects of highway tunnel construction on the groundwater environment.Firstly,this paper relies on the Shengli tunnel to use Visual MODFLOW numerical software to study the change characteristics of the groundwater seepage field in the tunnel area,and then establish the evaluation system of groundwater environment negative effects based on the variable fuzzy set theory,which applied to evaluate and analyze the Shengli tunnel.The main contents and conclusions of this research are as follows:(1)According to the engineering data of the Shengli tunnel,the groundwater seepage field in the tunnel area is simulated and analyzed.The results show that the construction of the Shengli tunnel will cause the groundwater level to drop in the tunnel area,forming a certain range of precipitation funnels,in addition the water level drawdown height and impact scope continue to increase with the construction footage.The maximum groundwater level drawdown during the construction period is 347 m,and the hydraulic influence radius is 0.8km at this time.After entering the operation period,the falling speed of the groundwater level in the tunnel area and the expansion speed of the precipitation funnel slowed down and tended to be stable.Both the water level drawdown and hydraulic influence radius of the tunnel area are approximately linearly negatively increasing with the tunnel construction elevation,and approximately linearly positively increasing with the tunnel hydraulic conductivity.(2)Based on the variable fuzzy set theory,an evaluation system for the negative effects of highway tunnel construction on the groundwater environment is proposed.Based on the evaluation index construction principle,an index system composed of three sub-systems consisting of groundwater replenishment factors,runoff conditions and tunnel engineering factors was established.The fuzzy analytical hierarchy process(FAHP)is used to calculate the weight coefficient of each index in the entire index system,and each index is graded and a quantitative method of the index membership is given.Then,the evaluation model and analysis steps of the variable fuzzy comprehensive evaluation method are described in detail.(3)Apply the variable fuzzy comprehensive evaluation method to analyze the impact grade of the Shengli tunnel on the negative effect of the groundwater environment.Sort out all the evaluation indexes of the Shengli tunnel and quantify them into the same interval value [0,100].The variable fuzzy comprehensive evaluation method is used to calculate the comprehensive membership degree vector of the index layer and the criterion layer,and then the water environment of the Shengli tunnel is determined.The characteristic value of the negative effect evaluation grade is (?) =2.70,and the influence grade is Ⅲ(moderate influence).This method can provide good theoretical support for the negative effects evaluation of highway tunnel construction on the groundwater environment.