Geological model of water preserved mining in Karst mountain areas in southwest China

There are a lot of coal resource in southwest China, where rocky desertification is very serious in Karst mountainous areas, especially in coal mining areas, which further promotes the process of rocky desertification. In order to coordinate the contradiction between coal mining and ecological environment protection in southwest China, the geological model of water preserved mining in Karst mountainous area of southwest China was studied. Taking Liupanshui coal field, especially Miluo Coal Mine of Fa'er Mining Area, as an example, the characteristics of "coal" and "water" in the southwest Karst mountain areas had been studied based on the analysis of the ecological, coal mining, tectonic geology and hydrological conditions in the study area using geological survey, mining exposure, mine hydrological observation, and groundwater borehole microscopic high-speed video obser-vation methods. The process of rocky desertification driven by coal mining in Karst mountain areas had explained. Then, the statistical analysis, three axis unloading experiment and water-electric similar simulation had been used to study the development height of the water conducting fissure zone in southwest China, the change of the rock mass in the whole subsidence zone and the response law of the ecological water level under the lateral seepage of the coal mining. The result shows that the coal mining in southwest Karst area leads to the decline of diving position, which promotes soil and water loss, and drives the progress of rocky desertification in Karst mountainous area in southwest China. This is the key problem of water preserved mining in this area. In the study area, the thickness of coal mining in the study area is small at 1~3 m, and the thickness of overlying bedrock is large at 800~1 000 m. The development of water conducting fissure zone is limited, and the performance of the aquifers is fine. The vertical seepage flow is weak, but the coal aquifers and the eco-phreatic exist lateral seepage, and the relationship of "coal" and "water" is the lateral seepage type. Under the typical mining geological conditions in the study area, a lateral coal pillar with a width of 80 m can be achieved, and the advance grouting can reduce the retention of water retaining pillars. This study can provide a basis for mining planning in Karst mountainous areas of southwest China. © 2019, Editorial Office of Journal of China Coal Society. All right reserved.