风积沙-黄土协同增强煤基固废膏体力学特性OA

To address the environmental problems caused by the large-scale accumulation of coal-based solid waste,paste backfill specimens were prepared by the orthogonal experimental method using coal-based solid waste and aeolian sand as the main aggregates.Through uniaxial compressive strength tests and microstructural analysis,the key factors affecting the strength of the backfill were identified.Com-bined with uniaxial compression stress-strain tests,the deformation characteristics and failure law of the backfill at different stress stages were investigated.The results show that the average 28 d compressive strength of the backfill is 13.9 MPa,meeting the 4.9 MPa strength requirement of Mahuangliang Coal Mine.The main factor affecting compressive strength is the proportion of aeolian sand and loess to ce-ment,whereas the fly ash-to-cement ratio has the least effect.The formation of compressive strength mainly arises from the synergistic effect of cement hydration and the pozzolanic reaction of active SiO2 and Al2O3 in coal gangue and fly ash.Coal gangue provides skeletal support,fly ash forms C-S-H gel through secondary hydration,and aeolian sand and loess optimize particle gradation,jointly impro-ving compactness and mechanical properties.When the coal gangue-to-cement ratio is 1.5,the fly ash-to-cement ratio is 1.5,the aeolian sand and loess-to-cement ratio is 0.5,and the mass concentration is 77％,the backfill exhibits a relatively high elastic modulus,limited crack development before the peak stress,and a marked increase after the peak stress.The crack evolution process undergoes the stages of closure,development,propagation,and coalescence,reflecting the whole process of internal stress accu-mulation,crack initiation and propagation,and eventual failure under loading.The stress-strain curve of coal-based solid waste paste shows four stages:Initial compaction,elastic deformation,yielding and plastic deformation,and failure.This study provides a theoretical basis and technical reference for the engineering application of coal-based solid waste in backfill mining.