Research On Geologic Environment Effects Induced By Coal Mining In Ecological Weakness Area And Assessment Techniques

Yushenfu mining district was located in transition zone between the hill ravine areaof Loess Plateau and Maowusu sand land, the earth's surface in this zone was coveredby rather thick unconsolidated formation because of drought and lack of rain for anaverage year as well as the sparseness vegetation. And in this mining district, theembedding depth of coal seam was shallow, the mining thickness was big and thethickness of overlying base rock also was rather thin. Thus, under the condition ofmining, the coal mining would often result in serious problems of geologicenvironment damages. In this study based on the prospecting test and investigation ofpresent state of the geologic environment in mining district, the impact of mining factorconditions on the geologic environment was analyzed. It thought that topographymorphology, thickness of sand bed, embedding depth of water level, thickness ofoverlying base rock on mining coal seam, coal seam thickness and so on are mainfactors to impact on the geologic environment in studying mining district, and then theimpact of mining activities on every factor of geologic environment was studied. GISwas used to carry out the space information quantitative management for every factor.Meanwhile, the theoretical analyzing method of support vector machine was adoptedto evaluate the present state of geologic environment in mining districtcomprehensively, and the change of geologic environment after mining was forecasted,the technological measures of geologic environment protection in ecological weaknessarea of coal mining were put forward. The main results are as follows:(1) Through testing research, prospecting and investigation of impact of coal mining onthe geologic environment in ecological weakness area and combined with formerstudied results, three kinds of geologic environment effects such as environmentaldeterioration of water, desertification and soil erosion caused mainly by the shallowcoal mining in studying area were obtained, among them, the coal mining causedthe upper water to enter into mine, thus, the variation of water flowrate, waterlevel and water quality was main behaviour of water environmental deterioration.Water level fall would result in soil salinization to cause soil desertification. Thewater environmental deterioration and soil desertification would cause the shallowecological degradation, surface soil deformation and damage strongly to result insoil erosion.(2) It thought by analysis that main impacting factors on the geologic environment instudying area were topography morphology, thickness of sand bed, embedding depth of water level, thickness of overlying base rock on mining coal seam, coalseam thickness and so on. Owing to bad original geologic environment condition,serious desertification and soil erosion in Yushenfu mining district, thus, theenvironment protection should be strengthened and controlled while coal mining isnot carried out.(3) The present state of geologic environment in Yushenfu mining district was dividedinto5kinds of evaluating subareas of geologic environment used by the theoreticalanalysis method of support vector machine and the space information quantitativemanagement of GIS to forecast the geologic environment change when coal mining,and the subarea map of evaluation and forecasting was given.(4) The coal resources development in Yushenfu mining district would not cause thegeologic environmental deterioration of all mines within mining district, no morethan in the places of water-rich and shallow embedding depth of coal, coal miningwould aggravate the environmental deterioration. Thus, these regions should beprotected and controlled with great emphasis when coal mining for the future.(5)For the coal resources development in Yushenfu mining district, according toforecasting results of the variation evaluation of environment quality and theconcrete geologic conditions of the environment engineering after and beforemining, the mining sequence should be optimized, the mining method shouldselected scientifically, and the comprehensive technology of "water–protectingmining" should be also actualized, so as to be the technological measures to realizethe coal resources mining and the geologic environment protection in ecologicalenvironmental weakness area.There are55figures,46tables and220references in the paper.