Research On The Impact Of Binchuan Coal Mine On The Geological Environment Of The Reservoir Area Of Ludila Hydropower Station

Ludila Hydropower Station is located on the middle section of Jinshajiang River of the border of Yongsheng and Binchuan County in Yunnan Province. While Binchuan Coal Mine is about 6km away upstream to the hydropower station. After excavating the coal seams out, the surface collapse will damage the buildings and traffic in the mining area. After impounding the reservoir, two coal seams will be under the water level. Therefore, the coal mine may have influence on the environment of reservoir and thus it has great theoretical significance and practical value to research it. This thesis discusses the impact of the coal mine to the geological, natural and engineering environment of the hydropower station, mainly from the aspects of the mine water quality, coal mine water condition, gob stability and mining slope stability.By means of the analysis of water quality, it is determined that the mine water after being treated will not effect the residents and reservoir water. Moreover, the hydrogeological classification is a simple one which is mainly filled by fissure water near fault zones and secondly by the weak pore aquifers.Through a detailed investigation on the ground of Binchuan coal gob, the quantity and extent of damaged buildings and forestry are determined. The surface movement and deformation mode is of continuous motion in the mining induced subsidence area. Meanwhile, main influencing factors of the surface movement and deformation are found out. After calculating the residual surface deformation by probability integral method, the coal shaft stability is calculated and checked according to the relevant procedures of engineering geological handbook. The result shows that the ground surface of the collapse area is relatively stable when there is no surface load. But when the unit pressure R comes to 5t/m2, the surface is not in stable state.Considering the topographical features and characteristics of coal seams of Binchuan coal mine, the influence factors of mining slope stability are determined. The slope stability under different condition of mining is calculated by using limit equilibrium method formulae. The result shows that when there is no rainstorm, the stability of the landslide body coefficient k is 1.683 and the landslide stability is good enough. In addition, when the landslide stability coefficient k is 1.227 under the condition of rainstorm and the landslide is in a quasi steady state.To sum up, the mine water has less influence on reservoir water, the residual deformation of the ground in mining induced subsidence area is bigger and the stability of slope gob area is good and will not harm to hydropower station. But because two coal layers will be submerged underwater after impounding, the reservoir bank must be treated with engineering measures in order to cut off the water channel and prevent reservoir pollution and coal mine shaft accidents.