Abstract
It is of great significance for engineering safety, economic benefits, environmental protection, and sustainable development to investigate the strata stability in filling mining with cemented rockfill. Consequently, this paper is based on a specific coal mine where we applied the fully-mechanized longwall mining and filling and designed a cemented rockfill material for which the particles satisfied the Talbot gradation. Uniaxial and triaxial compression experiments were carried out on the cemented rockfill specimen, which obtained the relations between the mechanical parameters (Poisson ratio, elastic modulus, compressive strength, cohesive force, internal friction angle, and tensile strength) and the particle size distribution of the aggregate. The excavation and filling processes in the coal seam were simulated based on the numerical software FLAC3D. The characteristics of the displacement and stress fields of the strata when the goaf was filled by cemented rockfill with different granule gradations were discussed. The influences of the particle size distribution and mining distance on the maximum subsidence displacement of the coal seam roof, internal stress of the backfill, and the stress of the rock mass in the coalface were analyzed. The feasibility and effectiveness of the filling mining with cemented rockfill to protect the integrity of the overlying strata were discussed. The results showed that optimizing the particle size distribution of the aggregate in cemented rockfill could increase the loading capacity of the backfill to improve the filling effect, effectively control the strata movement, and decrease the stress of rock mass in the coalface to reduce the potential danger.
Highlights
The mining of underground mineral resources causes damage to the overlying strata, which results in irreparable destruction to the aquifer and some mineral resources that the current technology cannot exploit [1,2,3,4,5,6]
The surface subsidence that occurs degenerates the plantable land, and large amounts of gangues and tailings are produced that waste land resources and pollute the environment [7,8,9]. These problems are increasingly serious with the development of mineral resources continuing to tend to the deep earth, which seriously damages the sustainable development that has been advocated for a long time [10]
The waste rock was obtained from a coal mine in China and composite Portland cement (P.C. 32.5R) was used as the cementing material in the cemented rockfill
Summary
The mining of underground mineral resources causes damage to the overlying strata, which results in irreparable destruction to the aquifer and some mineral resources that the current technology cannot exploit [1,2,3,4,5,6]. (4) In environmental conditions, including temperature, corrosion, conservation, and stress field, it is considered that creating more favorable environmental conditions can improve the mechanical properties of cemented waste rock [43,44,45,46,47,48,49,50,51,52,53,54,55,56] All of these studies are designed to minimize the strata movement and to protect the integrity of the underground structure [57,58]. The feasibility and effectiveness of filling mining with cemented rockfill to protect the integrity of overlying strata were discussed
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