Study The Safety Of Tiancheng Coal Mining Under The Yuecheng Reservoir In Hei Bei Province

As China’s main energy resource, coal occupies a pivotal position in the energysupply structure in our country. China’s coal resources are in urgent need development, but a large number of them have been located under railway, water, buildings. According to the incomplete statistic results, only in the existing country owned coal mine production, the quantity of coal which are located under railway, water, buildings is more than hundreds of tons. The coal can supply ten coal mine which production is 10 million tons annual for centuries. For many coal mine enterprises, with the overall depletion of shallow surface coal resources, the coal which are located under railway, water, buildings is also related to the company’s survival.The object of this study is Tiancheng coal mine which is located in Hebei Province. The main mining area of this coal mine is under the water of Yuecheng Reservoir. It is typical of surface water mining issues.The core of this study is the safety issues of Tiancheng mining under Yuecheng Reservoir, including two aspects: dam safety problem that the ground movement is caused by mining operation and will spread to the dam; and coal mine safety problems caused by mining water flowing fractured Zone whether turns on the surface water. In this paper, based on the full investigation on geological, hydrogeological conditions and mining technology, around the "Dam Safety" 、 "coal mining safety" two main ideas, the study found the following main results:(1)According to the probability integration method to calculate surface movement, maximum surface subsidence value is 2.97 m, main affects radius is 530 m, ground subsidence displacement of the minimum pitch of 10 mm dam containment line around is 2528 m.Based on FLAC3 D numerical simulation to calculate surface movement, maximum surface subsidence value is 2.98 m, main affects radius is 526 m, ground subsidence displacement of the minimum pitch of 20 mm dam containment line around is 2532 m.(2)According to the "three under regulation" empirical formula for calculating the height of water flowing fractured zone development, the development of water flowing fractured zone height is 52.4m. According to the literature on the "three under regulation" empirical correction, water flowing fractured zone of mining overall height is generally about 1.5 times slicing mining, the development of water flowing fractured zone height is approximately 80 m.Based on empirical parameter to calculate height of water flowing fractured zone development, taking into account the combination of lithology and structure of the 2nd seam roof, as well as a large factor in coal seam depth, take 18 times mining thickness,the development of water flowing fractured zone height is approximately 81 m.According to the engineering analogy method to calculate the height of water flowing fractured zone development, adjacent coal mining thick high split ratio is calculated into the natural coal mine, the development of water flowing fractured zone height is about 68.9m.Based on FLAC3 D numerical simulation to calculate the height of water flowing fractured zone development, After the excavation is completed, the final development of water flowing fractured zone height is 90 m.(3)According to the above calculation, When coal mining in the reservoir, the Surface Movement will not spread to the dam, which affect the safe operation of the dam;the height of Bedrock pillar is greater than the height of water flowing fractured zone by adding a protective layer thickness, the water flowing fractured zone will not conduct surface water bodies, Yuecheng Reservoir water body will not collapse into the ground,to threaten coal mine safety of Tiancheng Mining.