Simulation of groundwater flow in Tono mine

An extensive study has been carried out to estimate characteristics of groundwater flow in Tono region. As a part of this program, a simulation of groundwater flow around the shaft in Tono mine was conducted. For this simulation, a precise hydrogeological model was constructed. By the use of this model, three-dimensional groundwater flow in a saturated-unsaturated porous medium was calculated by means of finite element method. The results are as follows: (1) From the result of the parametric study, it was estimated that the hydraulic conductivity of Tsukiyoshi fault (1 meter thick in the model) is 1.0E-10 m/sec. (2) The result of simulation was in good agreement with pore water pressure observed around the shaft during and after the excavation. Therefore, the availability of the modeling and simulation have been confirmed. (3) The area where pore water pressure was changed by the excavation of the No. 2 shaft was within 100 meter from the No. 2 shaft in the upthrown side of Tsukiyoshi fault, and above 150 meter in the downthrown side. (author)