| In arid desert areas,the annual rainfall is low,the evaporation is large,and the serious impact of coal mining on the ecological environment in arid areas makes ecological management and restoration of Jnining areas imminent.The development of open-pit coal mines will further aggravate the shortage of natural resources in the mining area,and the stripping of the overlying strata during the mining process has greatly changed the original rock structure and aggravated the deterioration of the ecological environment of the mining area.Therefore,in order to achieve the goals of ecological restoration and irrigation water retention of the open-pit coal mines in arid desert areas,it is proposed to use the mudstone in the stripped material to reconstruct the aquifer to improve the water-holding capacity of the topsoil.Taking Hongshaquan open-pit coal mine as an example,mudstone(J2x2)and mudstone(J2.3sha)were initially selected as water-proof materials through geological exploration.The composition of the two mudstones was determined by XRD diffraction experiment,and it was found that they both contained kaolinite,illite,and quartz,and the mudstone(J2-3sha)also contained potassium feldspar and albite.Mudstones with particle sizes of 0.5 mm,1 mm and 2 mm and thicknesses of 5 cm,10 cm and 20 cm were selected for indoor soil column tests.The initial infiltration rate,the stable infiltration rate and the average infiltration rate of the water column liquid level drop rate,the wetting front drop rate,the initial infiltration rate of the cumulative infiltration rate,and the average infiltration rate are analyzed and evaluated,and the permeability coefficient and infiltration law of each scheme are obtained.The state analysis is carried out,and the physical experiment is verified by numerical simulation method.The results show that the mudstone(J2-3sha)has a strong anti-seepage ability,and the numerical simulation and physical experimental results have the same trend,which are both quadratic functions.Mudstone(J2-3sha)has good anti-seepage performance,but it collapses in water and has poor structural stability.The material properties of aquifers were studied with curing agent and fly ash as the content.Nine groups of ratios with different dosages were studied,that is,the dosages of soil stabilizer and fly ash were 6%,8%,10%,8%,10%,and 12%,respectively.Althrough uniaxial compressive strength test and variable head permeability test,the uniaxial compressive strength and permeability coefficient of each ratio are obtained,and the optimal model of TOPSIS scheme is constructed,and the curing agent:fly ash:mudstone(J2-3sha)is determined as the best ratio of 6:12:82.According to the optimal ratio,the surface reconstruction test was carried out in the outer dump+726 flat plate of Hongshaquan Open-pit Coal Mine.The thickness of the waterproof layer was 20 cm,and the thickness of the surface soil was 60 cm.According to the field measurement,the plants were planted after laying.After laying the aquifuge,the strength of the aquifuge met the specification requirements,and the water holding capacity of the soil layer increased from about 5%to about 10%.The aquifuge effect was obvious and the water holding capacity was enhanced,which could achieve the goal of ecological restoration irrigation and water retention of open-pit coal mines in arid desert areas. |
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