| Yushen mine, located in the central of Jurassic coalfield, is an important part of theenergy-chemical industry base in northern Shaanxi. The coal reserves are very rich in thisregion, which have30.17billon tons reserves explored up to now. Whereas, as a result of themining area is located in the southern margin of the maowusu desert and the loess plateauhilly-gully region bordering areas, the rainfall is scarce and the ecological environment isfragile in this region, and there are a series of ecological and environmental problems afterfirst and second-stage mining. The National Development and Reform Commission hasapproved third-stage mining to Yushen mine in2012, and planning construction scale is5700×104t/a. So in order to implement coal mining under water-containing and reduce thedamage risk to water conservation district caused by coal mining, how to draw lessons fromthe first and second-stage mining is a problem requiring to be solved immediately at present.On the basis of Yushen mine in third-stage planning areas and aimed at coal mining andwater sources protection simultaneous, this paper uses the data of mine geological,hydrogeological and the theories of coal geology, hydrogeology, engineering geology, rockmass mechanics, groundwater dynamics and numerical simulation to carry out the impactstudies on water conservation district caused by coal mining. The research results are asfollows:(1)Analyzed the hydrogeological and engineering geological characteristics of aquiferand aquiclude through collecting existing data, the results show that: the QuaternarySalawusu pore water is the main aquifer in this region, which has the water supplysignificance. Formed by stone loess and Neogene red clay, the soil layer is the main aquiclude,which widespread in whole region.(2)The space combination types of aquifer (aquiclude) and coal seam can be divided intotwo categories by constructing the2-2seam overburden space structure model. One isSalawusu aquifer, soil aquiclude, combination impermeable petrofabric and coal seam, andthe other one is Salawusu aquifer, soil aquiclude, Luohe aquifer, combination impermeablepetrofabric and coal seam.(3)The maximum height of water flowing fractured zone is26.5times of mining height by theoretical calculations, mechanical model and the simulation software FLAC3D.According to the result, the water flowing fractured zone cut through the upper soil aquicludeand connect with upper Salawusu aquifer of Hong Shixia water source in supply area, and thearea is1.49km2occupied0.07%in supply area. The area occupied0.47%in Yao town waterconservation district and Cai Tugou reservoir is6.33km2. The water flowing fractured zone ofSabina Nature Reserve has no impact on Salawusu aquifer in most regions.(4)By building regional hydrogeological model and software Visual MODFLOW, thispaper has analyzed the impact on groundwater flow caused by coal mining. The results showthat: groundwater seepage in Salawusu aquifer of Hong Shixia water source reaches1002.78×104~1050.05×104m3/a after mining25years, occupied3.04%~3.19%ingroundwater resource of Hong Shixia water source. While, groundwater seepage in Salawusuaquifer of Yao town and Cai Tugou water source reaches1666.00×104~1704.34×104m3/a,occupied7.33%~7.50%in groundwater resource of Yao town and Cai Tugou water source.There is a landing funnel in the south of DeLong mine, which drawdown is1.0~2.0m, and itwill has a certain impact on Sabina Nature Reserve.The above results have certain guiding significance for planning mine area, miningsequence, mining method and selecting mining technology, at the same time, quantitativeanalysis of the influence and degree on Hong Shixia water source caused by coal mining, andthese findings also have the reference significance to other similar mining areas. |
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