| The contradiction between the tunnel construction and the groundwater environment has always been a technical problem in the engineering world.Tunnel excavation often causes a large amount of groundwater to be discharged,thereby affecting the groundwater environment in the area,causing changes in groundwater seepage field,changes in hydrogeological conditions,and environmentally sensitive areas.Destruction,etc.,to study and master the law of the impact of tunnel engineering on the groundwater environment is the basic premise for effective protection of the groundwater environment.This article relies on the Dongquan Tunnel Project of the Chongqing East Ring Line,through on-site investigation and indoor testing to fully grasp the geological environment characteristics of the study area and the relevant parameters of tunnel design and construction.Finally,based on the analytic hierarchy process,the effect of Dongquan Tunnel on Tongjing Hot Spring was evaluated The following research results:（1）The Dongquan tunnel traverses the Tongluoxia anticline.The geological environment is more complicated.The tunnel mainly passes through the T3xj,T2l,T1j strata.The main lithology is limestone,karst breccia,dolomite,etc.,and the karst is relatively developed.The groundwater in the tunnel site is strongly developed,mainly karst underground cold water,which exists in the karst pipelines and erosion fissures in the T21and T1j strata,and moves along the rock strata,and finally discharges to the Wentang River.（2）Tested the isotopic composition and water chemical composition of Dongquan tunnel karst underground cold water and Tongjing hot spring underground hot water,the results show that Dongquan tunnel karst underground cold water DQ-1 chemical type is HCO3―Na·Ca type,others The chemical type of karst underground cold water is HCO3―Ca,and the underground hot water of Tongjing Hot Spring is SO4―Ca·Mg type.The content of TDS,Ca2+,Mg2+,Sr2+,SO42-,Cl-,and Si in the hot spring underground hot water is higher than that of karst groundwater,and the hot spring water and rock formation have experienced strong water-rock interaction.The karst groundwater in Dongquan Tunnel and the underground hot water replenishment of Tongjing Hot Spring all come from atmospheric precipitation.The recharge elevation of karst groundwater is 542.9m,the recharge elevation of underground hot water is 1174.1m,and the estimated thermal storage temperature of the hot spring is 143.1℃,mixed with hot and cold water The ratio is 77.6%and the circulation depth is 2570m.The underground hot water thermal storage structure of Tongjing Hot Spring is composed of three parts:heat storage cap layer,heat storage layer,and lower water storage layer.The Dongquan tunnel mainly traverses the heat storage layer and part of the heat storage cap layer.The vertical hydraulic connection of groundwater in the study area is strong,and the horizontal hydraulic connection is weak,and there is a certain hydraulic connection between the karst groundwater of Dongquan Tunnel and the underground hot water of hot springs.（3）Combined with the Dongquan tunnel construction plan,it was found that the blasting excavation will cause damage to the surrounding rock,causing local cracking and expansion of the rock mass until they are interconnected,thereby promoting the migration of groundwater in the rock layer;ANSYS/LS-DYNA blasting dynamics Numerical simulations show that the lateral influence range of blasting is 24.2m,the vertical influence range is26.0m,and the influence range outside the palm face is 9.6m.Tunnel water blocking mainly adopts surrounding rock grouting to block water.The waterproof measures include three-layer waterproof structure and low temperature resistant water-stop strips.The drainage measures are the central drainage ditch,the drainage ditch on both sides,the horizontal and vertical drainage pipes,the circular drainage blind pipe,etc..Tunnel construction can lead to massive loss of groundwater resources.The principle of"primary plugging and limited discharge"should be combined,and the discharge of groundwater in the Tongluoxia anticline should be reduced while ensuring the construction quality.（4）The evaluation index system of Dongquan Tunnel Project’s impact on the groundwater environment of Tongjing Hot Spring is proposed.An evaluation index system was constructed by integrating 29 influencing factors such as physical geography,engineering geology and hydrogeology,and tunnel engineering,and the impact evaluation level was gradeⅢ（medium）,and corresponding measures for protecting groundwater environment were proposed,and the groundwater in the area was restored as soon as possible The environment guarantees that the flow,water temperature and water quality of Tongjing Hot Spring will not be affected. |
