The analysis and application of granular backfill material to reduce surface subsidence in China’s northwest coal mining area

Abstract

In China’s northwest coal mining area, the excavation of shallow buried thick coal seams has caused serious damage to the phreatic water layer and induced deterioration of the ecological environment. Backfilling is a basic method of controlling the loss of groundwater and reducing surface subsidence. In order to reduce the porosity of the backfill material and control the compression ratio of the backfill body, the grain gradation of the local aeolian sand was studied based on the geological conditions of the shallow buried coal seam in the Yulin mining area, Shaanxi province. Subsequently, aeolian sand was selected as the backfilling aggregate, and tests were implemented. The optimum proportion and slurry concentration of the backfill material were then obtained. The engineering application shows that the strength and stability of the backfill body based on the close packing theory can satisfy the requirements of supporting the overlying strata, and the integrity of overburden strata is competent. The maximum accumulated surface subsidence was measured to be 38mm, indicating that the aeolian sand-based backfill material in shallow and thick underground coal seam mining is able to protect the eco-environment and control the geo-environmental hazards, which are critical for the sustainable development of the mining industry and economic growth.

Sustainable Development of Resources and the Environment: Mining-Induced Eco-Geological Environmental Damage and Mitigation Measures—A Case Study in the Henan Coal Mining Area, China

“…(2) Filling mining Filling mining [13] involves filling the goaf in the process of coal mining, and constructing the structure system of "filling body-overlying strata-key strata" to control the deformation of overlying strata and surface. It is widely applied and it can be effective in areas where the overburden and surface deformation requirements are strict.…”

“…Chen et al [12] conducted a series of field monitoring exercises and comparisons with previous studies, and acquired the evolutionary characteristics of dynamic subsidence parameters and surface cracks in fragile-ecological mining areas. Bai et al [13] analyzed the application of granular filling materials to reduce existing surface subsidence in the northwestern coal mining areas of China. Guo et al [14] studied the solid filling mining technique as a means of subsidence control and farmland conservation.…”

Research on complex air leakage method to prevent coal spontaneous combustion in longwall goaf

“…China is the largest coal-producing and consuming country in the world, and 90% of coal comes from the longwall mining faces [1, 2]. During longwall mining, the underground coal fires are a major hazard threatening production safety [3–5].…”

Analysis and Application of Backfill Mining in Thin Coal Seams for Preventing Building Damage

“…Therefore, to prevent surface building damage and other geological disasters controlling overburden strata is key. By contrast, backfill mining, an important technique in green mining, is a significant revolution in ground control (Bai et al 2018b). It has been developed to solve the global problems mentioned above, especially in 'under-three' mining, such as hydraulic backfilling, solid backfilling, and high-water material consolidation tailing backfilling (Bell & Genske 2001;Huang et al 2011;Kostecki & Spearing 2015).…”