Eco-geological environment comprehensive management model of combined mining area of open-pits and underground mines in frigid plateau region

Environmental pollution and ecological destruction caused by mineral resources exploitation are the main factors of ecological environment degradation. For high altitude areas where have the characteristics of drought, cold and barren soil, the problems such as alpine meadow damage, permafrost degradation and biodiversity sharp decline induced by coal mining are more prominent. On the basis of engineering geological exploration and ecological environment investigation, the eco-geological environmental problems and their evolution law of the Muli coalfield in Qinghai Province since 2003 were analyzed comprehensively. The results show that long-term large-scale coal mining has led to the rapid degradation of the ecosystem, the significant reduction of ecological service function, the destruction of topography and geomorphology, and the increasing risk of ecological geological environment in the mining area. The ecological environment needs to be repaired urgently, however, the adverse factors such as alpine hypoxia, lack of topsoil, and difficulty in self-renewal of regreening plants are the problems that must be faced by ecological restoration projects. In view of the above destruction problems and treatment technical problems, the comprehensive management of eco-geological environment of Jiangcang No. 1 mine, which is the open-pit and underground combined mining area in the frigid plateau region, was taken as an example. The concept of "landscape, forest, field, lake and grass are a community of life" was followed. The principle of "saving first, protecting first and natural recovery first" was maintained. The idea of "reliable technology, reasonable economy and rule by law" was as a starting point. Drawing the lessons from existing experience, according to the eco-geological environment comprehensive management ideas of "suit measures to local conditions, zoning control, eliminate hidden dangers, close to the natural", the integrated management mode of pit and dump site was proposed based on "slope cutting and shaping of dump site + backfilling and slow slope of mining pit + roadway protection+rock wall regulation + microtopography remodeling + soil reconstruction and vegetation restoration". Based on the theory of "geological disaster prevention and control+ecological environment restoration", the key technical system of comprehensive management of eco-geological environment in plateau alpine mining area was constructed. The lack of green topsoil was solved by using the topographic and geomorphological reconstruction technology based on "maximum exposure of in-situ soil, priority utilization of stripping soil, and appropriate combination of artificial soil" and the rapid soil improvement and reconstruction technology based on "basic volume increase of decomposed sheep manure and optimization of commercial organic fertilizer". The problem of deformation and instability of freeze-thaw high-steep composite slope was solved by using slope stability control technology combined with backfilling and slope cutting. The backfill construction technology of ground "partition construction-bidirectional backfill-slow down the slope while moving forward" and the roadway protection technology of underground "anchor-grouting strengthening support" were used to solve the problem that shallow heading engineering is vulnerable to backfill disturbance. © 2021, Editorial Office of Journal of China Coal Society. All right reserved.