Stability analysis of backfill body-roof synergistic bearing considering the age intensity

ZHAO Bingchao; WANG Ruifeng; WANG Jingbin; CHEN Haonan; YANG Zhonghao; TUO Yongsheng

doi:10.11799/ce202508016

Abstract：In order to improve the recovery rate of coal resources and dispose of a large amount of coal-based solid waste,based on the integration of excavation and filling of inter-face coal pillars,considering the influence of age on the strength and bearing capacity of the backfill body,the evolution law of the strength of the backfill body with age under different cement contents was studied through laboratory tests.It was found that the cement content was positively correlated with the strength of the backfill body,and the strength of the backfill body increased exponentially with age.Based on the theory of elastic foundation beam,the cooperative bearing capacity model of backfill body-roof in the process of excavation-filling was established,and the roof deflection equation of each region in the process of excavation-filling was given.FLAC3D numerical simulation was used to explore the influence of backfill body cement content,excavation-filling distance and excavation-filling speed on backfill body stress and roof subsidence in the process of excavation-filling,and the stability of backfill body-roof cooperative bearing structure under different excavation distances in the process of excavation-filling was analyzed.The results show that in the process of excavation-filling of inter-face coal pillars,the higher the cement content and the smaller the excavation-filling spacing,the faster the strength formation time of the backfill body and the less the roof subsidence.The faster the excavation and filling speed,the shorter the age of the backfill body in the filling area,the lower the strength,the worse the bearing effect,and the more serious the damage of the plastic zone of the roof.With the advancement of the excavation distance,the bearing capacity of the backfill body gradually increases,the roof subsidence rate gradually decreases,and the backfill body-roof cooperative bearing structure gradually stablizes.