Mine Inflow In Open Pit Mine Dynamic Simulation Study

Mine Inflow refers to opening up from the mine to the stoping process, the unit time of water flow into the pit(including wells, lane roadway system). It is an important indicator to determine the type of Hydrogeology of deposit,the complexity of the deposit hydrogeological conditions and evaluating economic and technical conditions.Taking a opencast coal mine in Inner Mongolia, for example, this paper collected 146 borehole data in the study area and the surrounding.And three times groundwater level measurement of the study area have been taken.Based on these information, mine and the surrounding earth formations and hydrogeologic conditions are fully understood.Through the collection of information, three-dimensional geological model and groundwater numerical model of the study area have been built by GMS software. And on this basis, the mine water drainage process have been generalized into constant flow and constant head sparse drainage phases.With the first mining area and the second mining area as an example, the use of Well module simulates the constant flow stage by drainage. Drain module simulates constant head dewatering stage. In this method, a continuous time-varying dynamic simulation of total amount of pit dewateringand mine inflowwas achieved. Through the terrain changes reasonable generalization,we simulate the dynamic process of the second mining area mining sparse drainageafter the first mining area exploiting completion. This analog method can not only control the target water level more accurate by using Drain modules, but also show the gradual drainage process byWell module.After simulation, the results of the present study was the following:(1) Identification of the model has been verified on the monitoring level correction, the fit is good. Through the models,groundwater balance were calculated in the study area. Simulation results show that the total period of groundwater recharge is 1.7923 million m3/a, the total excretion is 2.0301 million m3/a, and the difference between the balance is 237800 m3/a, a negative balance.(2) Within one year of the first mining area total mine dewatering water is 5211 m3/d, constant-head stage by drainage of mine inflow of 2310.97 m3/d. Mine Inflow years changed a little in August to reach a maximum of 2364.96 m3/d, 11 month of the year minimum, to 2230.45 m3/d.(3) Due to the first mining area of influence, the initial levelof Second Mining Area is low, so the second mining area one year total mine dewatering water significantly reduced compared with the first mining area, is 2647 m3/d. Mine Inflow in July reached a maximum of 1902.05m3/d, at the end of 10 mine water inflow to a minimum, in order to 1750.72 m3/d, the average mine water inflow during the year was 1817.03 m3/d. It has been reduced compared with the first mining area.(4) Mine drainage had a huge impact on the groundwater flow field of study area. During mining the first mining area, unconfined aquifer water table of the surrounding decline about 14~16m, confined aquifer’s biggest drop is about 50 m, forming a huge cone of depression. Second Mining Area of the initial level is low, but after the water level is still significantly decreased by drainage.