Research on calculation method of the scope of groundwater environmental impact assessment for mountain tunnels

It is urgent to study on groundwater environmental impact assessment of mountain tunnel projects as the growing tension between tunnel construction and groundwater environment protection. Determination the assessment scope is an essential step while few of the researches on this subject were carried out except some qualitative analysis. In this study, a preliminary exploration on how to determine the assessment scope of groundwater was obtained with both quantitative calculation and qualitative analysis. Of note, it is difficult to determine assessment scope accurately as the successful determination depends on various factors. But based on predicting the water gushing effected area of tunnel, it can be comprehensively determined combined with hydrogeological conditions in tunnel site. By analyzing existing calculation methods of the effect range of tunnel water gushing, a new prediction method was derived from water yield formula of infiltration channels, and applied to two typical tunnels in Karst area and Redrock region southwest respectively and the scopes of their evaluation were also predicted out combined with hydrogeological conditions in tunnel sites.