Numerical Simulation Study On The Influence Of Different Mining Conditions On Loose Aquifer In Thick Loess Covered Coal Mine

China is a big country of energy, coal reserves ranking first in the world, mainly in Shanxi, Inner Mongolia, Gansu, Ningxia, Shaanxi and other parts of the Northwest region. Affected by the regional geological structure and crustal evolution, in many parts of the Quaternary thickness generally larger, strata often exist rich water of better loose aquifer, especially in Quaternary Pleistocene aquifer, is the main water supply source for the production and life in the coal rich region. In recent years, With the development of the coal mining activity, a series of environmental geological problems have emerged, the groundwater level in the loose aquifer is generally declining, Some areas have formed groundwater drawdown funnel and even the aquifer is drained, it has seriously restricted the local economic development and the normal life of the residents. Therefore, in the thick loess area, to study the influence of coal mining on the groundwater in the loose aquifer, which has important theoretical guiding significance for the protection of groundwater resources and the protection of groundwater resources.This paper takes Shanxi County of Tunliu Province in Changcun Coal Mine S6 mining area as the research background, based on the geological environment conditions in a certain range, the three-dimens ional groundwater flow numerical model is established by Using GMS software, to study the influence of coal mining under different mining conditions on the groundwater of loose aquifer. By changing the permeability of different parts of the overlying strata in the goaf, to study on the development of water flowing fractured zone in different height(0m, 25 m, 50 m, 70 m, 90 m, 110 m, and 140m) and the different time periods(1 years, 3 years and 5 years) on the groundwater of the loose aquifer.For different simulation schemes, respectively calculated different period of the influence of groundwater depression cone and the maximum water level drop in the central of groundwater depression cone.Through the identification and adjustment of the model, the model can predict the level of the model. For different simulation scenarios were calculated S6 mining exploitation in different periods after landing funnel of the scope and impact of the funnel center at the maximum drawdown and prediction results.After analyzing the results of the study, the main conclusions are drawn as follows:1. Comparaed with the influence on different height of water flowing fractured zone to groundwater, we can draw the following conclusion that: different height of water flowing fractured zone is different to the groundwater level in the loose aquifer. Generally speaking, with the increase of height of the water flowing fractured zone, the influence of the loose aquifer is increasing exponentially. Simulation studies show that: the height of the water flowing fractured zone is less than 50 m, the influence of groundwater on the loose aquifer is the most significant;when their distance is between 50 and 110 m, the influence of groundwater on the loose aquifer is stable; when their distance is larger than 140 m, there is no influence on the groundwater in the loose aquifer.2. Comparaed with the influence on different period after coal mining to groundwater, we can draw the following conclusion that: the influence degree of different periods after coal mining on the groundwater of the loose aquifer is different. As a whole, with the extension of time, the influence of the loose aquifer is gradually weakened. Simulation studies show that: the influence of the loose aquifer is most significant in the time of about 500 days after the coal mining; as time goes on, it slows down the impact of the ground water;about 5 years after mining, the influence of the loose aquifer tends to be stable.