Abstract: An acid reservoir is planned to be constructed in a mined-out area of mine.In order to demonstrate its feasibility，a three-dimensional model of mined-out area and surface was built with 3D mining software SURPAC according to the intermediate entry plane of every stope and the topographic map.After divided into blocks，the calculation model was generated in FLAC3D by the interface program of SURPAC-FLAC^3D，and then the stability of reservoir area is evaluated by calculation and analysis.Through the numerical simulation，maximum surface settlement on mined-out area is about 9.5 mm in the current situation，and a new increased settlement is about 7.1 mm after water storage in reservoir.The simulation results show that the present mined-out area is stable.The surface settlement on mined-out area is within the allowable range of building settlement after water storage in the reservoir.This provides a theoretical basis for the feasibility of building the reservoir.The field testing of blasting vibration is made to study the effect of blast vibration on stability of the reservoir area.The results show that the maximum vibration velocities are all within allowable safe range，and blast vibration has no obvious effect on safety of the acid reservoir.Some suggested measures were proposed on this basis.

Key words: Reservoir, FLAC^3D, Numerical simulation, Maximum settlement, Blast vibration, Vibration velocity, Stability