| The mining industry is one of the important industries for human’s living and development. With the rapid development of economy, society, science and technology, people’s requirement for resources is increasing, which make the mining industry become an important industry. But at the same time, it also brought a lot of geological environmental problems. These problems brought many inconvenience to people living near the mining areas, also affect the economic and social development in this regional. So clarifying these problems, understanding the present situation, and taking scientific countermeasures is very important.In this paper Yangcaogou coal mine was taken as the research area, three typical types of mine environmental geological problems:aquifer drainage&destruction, water and soil pollution, land subsidence, which occured in the area that were influenced by the the mining activities were studied. Field observation, sampling, testing, laboratory analysis, etc, had been carried out, mechanisms, present situation, developping trend and their replied measures were also discussed, the main methods and results are as follows:(1) Firstly confirm the current and end-mining scope of gob according to the actual mining situation and future mining plan of Yangcaogou mine. Then author uses the ratio of depth and thickness drawing the line of zone that subsidence may occur within the mine-out area preliminary. In addition, catastrophe progression method is put into use to examine the previous result.Considering the development law of ground subsidence and actual situation of Yangcaogou mine, subsidence area is divided according to the stop time of subsidence in different location. Calculate the maximum ground subsidence value of subsidence area, then rate three subsidence hazard level and divide the subsidence area. Finally, some suggestions were put forward to the control and rectification of ground subsidence according to the present situation and development trend of subsidence problems in research area.The research results showed that current ground subsidence area is for an area of6.5km2. As coal mining going on, subsidence will have a further development. Finally, subsidence area will cover7.4km2. Ground subsidence in southern part of research area has stopped, the mining activity is concentrated in northern part recently. Ground subsidence of the newly formed mined-out area is still developing and its terminal time will be or after the year of2018. The Sinking value of subsidence area is normally3to10meters and the maximum up to13meters. Ground subsidence has caught various damage as its forms are integrity sink and collapse pit.(2) Surface water, groundwater and the mine drainage samples were collected and analyzed in the study area, adopted single factor pollution index method, Nemerow comprehensive pollution index method, and the BP neural network method based on factor analysis to evaluate water quality of the samples. The evaluation results show that the quality level of surface water were mostly Ⅳ and Ⅴ in the study area, and permanganate index, COD, and total nitrogen exceeded standard seriously. Research showed that the surface water quality is mainly affected by the mine drainage based on the analysis. the quality level of groundwater were mostly Ⅲ and Ⅳ in the study area, and ammonia nitrogen, permanganate index, and total iron exceeded standard seriously. The groundwater quality is mainly affected by agricultural production, mining hardly impacted the groundwater quality in this area.The spatial distribution and variation characteristics of the five heavy metals (Cd, Pb, Cu, Cr, Zn) were analyzed, adopted single factor pollution index method, Nemerow comprehensive pollution index method to evaluate heavy metal pollution actuality in soil, using the potential ecological risk index method to evaluate the soil potential ecological harm. The evaluation results show that the soil heavy metals pollution mainly concentrated around the coal gangue dump, the soil environment quality is better as a whole in the rest of the study area. The results of potential ecological risk assessment showed that the trend of potential ecological harms decreasing with the increased distance from the coal gangue dump. Finally, according to the change trend of soil and water environment in the studied area in the future, we put forward some suggestions about treatment measures for coal mining waste water and coal gangue for Yangcaogou mine.(3) The mechanism and influencing factor of aquifer breakage were discussed according to the theories and methods of environmental geology, then the definition of aquifer breakage caused by mining was given, and evaluation system of level of aquifer breakage was established by the changes on amount and structure of aquifer, the levels of aquifer breakage are divied into mild, moderate and severe.Considering the hydrogeology survey results in the study area and factors such as mine geological, hydrogeological conditions, buried depth of coal seam, mining methods, calculated the height of water conducting crack zone produced by the mining, the influences on unconfined aquifer and confined aquifer in the study area and the current situation were analyzed. According to the established evaluation system, the level of aquifer breakage in the study area was evaluated. Finally in combination with the practical situation of Yangcaogou coal mine, measures of controlling the aquifer breakage were put forward.Studies have found that the breaking height of overburden strata above the goaf caused by the water conducting crack zone is between53.44m and54.25m, due to geological structure and mining methods, unconfined aquifer in the north of mining industrial square which is in southern study area is influenced, but the area is small, only0.36km2, in this area the drainage of unconfined water is more serious. Original aquiclude K1y3-c3in the study area was broken by water conducting crack zone, meanwhile it was the impermeable base of the aquifer K1y3-c4. According to the evaluation criterion proposed in this paper, the extent of aquifer breakage is "serve". |
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