Research of the Backfill Body Compaction Ratio Based on Upward Backfill Safety Mining of the Close-Distance Coal Seam Group

Abstract

During upward backfill mining of the close-distance coal seam group, the reasonable design of the backfill body compaction ratio (BBCR) of lower coal seam goaf plays a key role in controlling overburden strata movement and deformation. In this paper, the feasibility discrimination method of upward caving mining was adopted; it was found that when the coal seam spacing was small, the recovery was not possible due to the instability of the upper coal strata equilibrium structure caused by the mining. Hence, the upward backfill mining method was proposed; combined with the migration control mechanism of backfill mining overburden strata, the dynamic evolution of crack propagation height of overburden strata during upward backfill mining was analyzed. Based on that, a layer spacing-BBCR-mining height (L-R-H) prediction model based on multiple linear regression analysis was established and the BBCR of close-distance coal seam group safe upward mining was determined combined with the engineering background. The results demonstrate that the main controlling factors of crack propagation in overburden strata during upward backfill mining were BBCR and mining height; the crack propagation height in overburden strata caused by mining decreased exponentially with the increase of BBCR and increased with the increase of mining height linearly. The lower coal seam engineering safety BBCR of upward backfill mining in the Dafosi Coal Mine was 87.2%, and the close-distance coal seam group safe upward mining was realized.

Non-uniform failure and differential pressure relief technology of roadway under irregular goafs in deep close-distance coal seams

“…In order to further analyze the stress distribution of roadway surrounding rock under residual coal pillar, a cross-section is made along the excavation direction of roadway, and a stress model of any point on the floor within the influence range of residual coal pillar is established based on the half plane theory 25 , 26 , as shown in Fig. 5 .…”

Geodetector-Based Livability Analysis of Potential Resettlement Locations for Villages in Coal Mining Areas on the Loess Plateau of China

“…The annual coal production of the Dafosi mine is 8 million tons, the No. 4 coal at the depth of 350-450 m is the main mining layer, with an average mining thickness of 9 m, and the long-walled working face mining technique is applied [36]. After mining, an obvious collapse area has appeared on the terrain, and the maximum ground subsidence in the collapse area will exceed 3 m. The evaluation of the livability of the resettlement area selection must be made in advance.…”

Study on Deformation Response Law of Surrounding Rock in Solid Backfill Mining Stope

“…Under the principles of "safety, economy, and environmental protection" and "safe, efficient, and green" mining has become the national development concept; therefore, the research of eco-friendly mining methods is the theme of current and future resource development. In recent years, with the large-scale mining of coal resources in China, the mining conditions are deteriorating, and the trend of coal resources under "three-body" is increasing year by year; therefore, it has a very broad application prospect to promote and develop the effective method of coal mining under "three-body" [5,6].…”