| Huaying Mountain is a natural barrier to the east edge of the Sichuan Basin,the compound fold and fault structure of which is very complex,and the carbonate rocks of Triassic and Permian are widely exposed,in the process of tunnel construction,there is a high risk of karst water inrush and geological environment negative effect,it is urgent to systematically and comprehensively study the development law of karst and the evolution law of karst underground water flow field and geological environment under the influence of human engineering activities in Huaying Mountain,so as to provide certain theoretical support for the prediction of water inrush and geological environment protection of karst tunnel in Huaying Mountain and East Sichuan parallel ridge-and-valley area.Through the analysis of existing work and research literature in Huaying Mountain area,combined with the field hydrogeological survey,this paper summarizes and analyzes the characteristics,periods and influencing factors of karst development in the middle part of Huaying Mountain,divides different karst water systems from the perspective of water system,and discusses the basic hydrogeological conditions of each karst water system in detail.This paper,by using numerical simulation methods describe compound fold in the middle of Huaying Mountain three-dimensional geological model,on the part of natural groundwater flow field,and in the middle of the Huaying Mountain coal mine tunnel under the disturbance of the groundwater flow field,G42 Huayingshan tunnel under the influence of groundwater flow field in the inversion analysis,and proposed to adjacent road Huayingshan tunnel construction of the groundwater flow field,forecast the environment impact of analysis and research,the main research results are as follows:(1)The groundwater circulation and the secondary karst water system in the research area of Huaying mountain are divided according to the theory of groundwater system.Huaying mountain area deep large regional groundwater flow circulation mainly controlled by the Jialing river,the Yangtze river such as themselves a valley,but the deep groundwater circulation in addition to control themselves a valley,is obviously controlled by transverse deep valleys,and therefore Huaying mountain of deep groundwater cycle can be divided into the south,middle and north three parts,respectively is southern(Jialing river to Huayingshan grand canyon/Yangjia river),middle(Huayingshan grand canyon/Yangjia river to Longmen gorge river),north(Longmen gorge river to Zhou river),the karst water system in the research area is divided from the perspective of water system and its hydrogeological conditions are discussed.Karst groundwater in the study area is divided into three first-grade karst water system,and first-grade karst water systems are Tianchi syncline karst water system(Ⅰ),Baodingshan anticline karstic water system(Ⅱ),Lushuidong anticline karst water system(Ⅲ).(2)An elaborate three-dimensional hydrogeological model is established in the study area to carry out inversion analysis on the evolution process of karst flow field under the influence of natural and coal mine adits before the influence of tunnel engineering.Perpendicular to the rock to decorate in the scope of the study area,a total of 24 profile,the profile density of article/1-1.5 km,decorate in the section line read each rock drilling elevation,altitude data of the statistical sorting using GMS,Modflow software describe the complex three-dimensional drape hydrogeological model,boundary and initial conditions of the input model,the simulation and underground water in and out within the scope of the research area of each river,overland flow,such as rivers flow hydrologic comparison analysis,and thus for the model identification and calibration,after the stable operation of the anti performance research of natural flow field,Result is shown in green water hole anticline overthrow of karst conduit of karst groundwater flow field disturbances,along the pipe forming obvious drop a funnel,and in the green water hole in coal tunnel under the common effect of drainage,the anticline capsized section of the underground water level affect the broader,on both sides of the tunnel form a funnel,karst water drop funnel because along pipeline is adit captured and gradually disappear.(3)The causes of water inrush in the west section of G42 Huayingshan tunnel and the underground water flow field are analyzed.The main reason for the water inrush in the western part of Huayingshan tunnel is the branch of the underground river pipelines in Dongwan and Guangdongwan,which are connected with the large area of karst negative terrain on the north side of the tunnel,the excavated tunnel has become a new drainage standard,and the karst groundwater on both sides of the tunnel is collected here,causing the underground river in Dongwan and Guangdongwan on both sides of the tunnel entrance to break the flow,and the drainage volume of the tunnel in Lushuidong coal mine and Tianchi coal mine adits to reduce the flow.(4)The evolution process of underground water flow field and environment after construction and completion of G42 Huayingshan tunnel is analyzed.G42Huayingshan tunl process based on the differences of aquifer and the measured water inflow in tunnel construction is divided into nine sections in Modflow software simulation,the results show that the tunnel import Jialingjiang Formation,the Member-2 of Feixianguan Formation period of construction,its influence on the groundwater flow field is small,the construction to the Member-4 of Feixianguan Formation,Permian System aquifer when the water level drawdown,influence scope,the biggest drop up to 120～150 m,the farthest reach up to 2 km above,coal mine tunnel,underground river water pipeline,the flow field are affected;In the eastern limb of the anticline,the influence range of the passage through each aquifer is relatively small,but the hydraulic gradient in the form of descending funnel is relatively large.The continuous drainage of the tunnel caused the underground water level to drop 3.5km to the north and 2.5km to the south,and the flow was broken in Dongwan and Guangdongwan,and the flow was reduced in the coal mine adit,and some spring points disappeared.(5)The evolution process of underground water flow field in 10 years after the excavation of the tunnel is predicted.The simulation results show that the underground water level of the proposed tunnel reaches a depth of 30～40m to the core of Tianchi syncline and the influence range is 500～1000m;the water level of the Permian System formation in the west limb of anticline reaches a depth of more than100m;the influence range of the tunnel on the north side is 1.0～1.5km and the south side is about 500～1000m,at the same time,compared with the water inrush accident of G42 Huayingshan tunnel in Changxing Formation,the water inrush of the proposed tunnel in the Permian System aquifer of the core of Tianchi syncline and the Lushuidong anticline is relatively large,with the maximum water inrush of 39186.51m~3/d and the total water inrush of 126787.1 m~3/d,and the influence scope,depth reduction and water inrush risk of the rest sections are relatively small.(6)The evolution of groundwater flow field in proposed tunnel with lining or without G42 Huayingshan tunnel was compared.After 10 years of relatively waterproof lining for the proposed tunnel,the groundwater level in the vicinity of the proposed tunnel recovered to a range of 550～600m with no obvious descending funnel,in the absence of G42 Huayingshan tunnel,the influence of the underground water flow field in the research area is mainly controlled by the coal mine adit,the underground river pipeline and the proposed Huayingshan tunnel.The underground water field around Hongyan township is mainly controlled by the proposed Huayingshan tunnel,the influence range of the underground water level is more than2km on both sides of the tunnel,and the depth drops to more than 60m.However,compared with the G42 Huayingshan tunnel,the underground water level on the north side of the proposed tunnel has recovered from 540m to about 600m. |
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