Study On The Impact Of Construction On The Water Environment And Control Technology Of Water-rich Large-span Mountain Tunnels

With the rapid development of tunnel construction in China,the construction environment of tunnel is becoming more and more complex,and the special geological conditions are also increasing.There are many mountain tunnels with high water pressure and rich water stratum,which involves many problems of groundwater treatment.In the process of mountain tunnel construction in China,the treatment of groundwater is mainly drainage,which will inevitably damage the formation water environment.Excessive discharge of groundwater during tunnel construction and excavation,on the one hand,is easy to cause the groundwater level to drop,damage the ecological environment,affect the growth of surface vegetation and the normal living water of residents,on the other hand,it is also easy to threaten the stability of tunnel surrounding rock and lining.In order to effectively protect the surrounding formation water environment in the process of tunnel construction,based on the guiding principle of "mainly blocking,combining blocking and drainage,and limiting discharge",relying on the Yanglin tunnel in the southeast section of Kunming Ring Expressway.In this paper,data investigation,numerical simulation,field measurement,theoretical analysis and other research methods are used to carry out the research on the law of the impact of tunnel construction on water environment,the control benchmark and control technology of water environment protection.The main achievements are as follows:(1)By means of numerical simulation and field measurement,this paper analyzes the influence of tunnel construction on surrounding formation water environment,explores the influence law of tunnel construction on seepage field under different factors,and gives the relationship formula between tunnel drainage and water level drawdown.(2)Based on the research and analysis of the distribution characteristics of the tunnel vegetation and the domestic water consumption of the residents along the tunnel,the control standard of the underground water level in the tunnel site is proposed by using the ecological hydrological model and the residential water consumption model with well water as the water source,The calculation method of tunnel limited drainage based on the control standard is given.(3)According to the limited drainage standard of each section of the tunnel,based on the study of the tunnel waterproof and drainage system and related design parameters,the waterproof and drainage measures meeting the limited drainage standard of the tunnel are proposed.The above research results can provide some reference for the design and construction of other similar mountain tunnels in high water pressure and water rich strata.