Study On Method Of Determining Water Drainage And Limiting Drainage Standard For Mountain Tunnel Based On Ecological Requirement

In recent years, people pay more and more attention to the harmony of tunnel engineering and tunnel site area surrounding environment. In the process of the construction of tunnel engineering, tunnel engineering and ecological environment of tunnel site area are increasing contradictions, including the groundwater environment, ecological environment of vegetation, residents living environment. Due to the tunnel excavation drainage groundwater, thereby it is easy to break ecological environment of the tunnel site area. how to determine the most appropriate limit emissions and establish a suitable underground water drainage criterion of mountain tunnel engineering, is an urgently problem in the tunnel engineering.Based on mountain tunnel as the research object, this paper adopts literature researches, field investigation, theoretical analysis and calculation, groundwater dynamics, numerical simulation methods to carry out the research. By the method of literature research and field investigation, to analyze the main types of groundwater of its interaction with tunnel, and the existing prediction methods of tunnel water inflow, including their advantages and disadvantages and applicable condition. the main means of theoretical analysis and calculation were used to forecast tunnel water inflow base on the groundwater dynamics method. Then mountain tunnel water drainage was determined from the perspective of ecological water requirement for vegetation based on areal-well methods from the groundwater dynamics. Finally, according to the water inflow and mountain tunnel water drainage, the selected common calculation parameters value in the mountain tunnel, to determine the suitable for most mountain tunnel groundwater discharge standard. The main research content is as follows:(1) by summing up the existing prediction method of tunnel water inflow and considering on the engineering practical experience, discussing the advantages and disadvantages of all kinds of water inflow forecast method and scope of application, the tunnel water inflow prediction method is proposed in this paper.(2) From the perspective of ecological water requirement for vegetation, base on the areal-well in groundwater dynamics theory to deduce the relationship between the underground water level and time, water drainage. Through the total emissions of groundwater and the total recharge of groundwater from rainfall infiltration to analysis on the balance of groundwater, water drainage method for determining the balance of groundwater was presented in the mountain tunnel.(3) Selecting the range values of parameters from rock soil mass in the most of southern provinces, such as the common permeability coefficient, water level and groundwater head height. base on vegetation ecological balance to determine the most suitable of mountain tunnel groundwater limiting drainage standard; put forward to the determined method of tunnel limit water drainage under this condition of water inflow is too heavy to effectively control.