Physical and chemical analyses of ground-water by impacts of tunneling at coastal urban region in Busan

부산시 해안 인근 지역에서의 터널 굴착에 따른 지하수 거동 영향 평가

In the case of tunneling, the equilibrium state of hydro-geologic environments destroy and change abruptly in some section of whole works. Specially, it's very possible for seawater to intrude toward the site of tunnel if the field is nearly located in a costal region. In this study, we have evaluated the mechanism related between groundwater flow and seawater intrusion that by impacts of tunneling. Various hydro-geological field tests have performed for getting four representative hydrogeologic properties of geologic formations such as transmissivity (T), storativity(S), longitudial dispersity(${\alpha}_L$), and effective porosity($n_e$). For the effect of tunneling, the numerical model was first simulated based on the governing equation of groundwater flow. The results showed that the maximum drawdown was 17.2m and the total inflow into the tunnel had the range from 0.48 to $3.63m^3/day/m$. Secondly, the three dimensional numerical model was analyzed to investigate a characteristic of seawater intrusion based on the previous simulated results of groundwater flow. The results showed the seawater moved as the range of $200{\sim}220m$ from the initial interface between seawater and groundwater toward the tunnel.