| Based on the research background of the backfill treatment of historical minedout areas,and the recovering of rib pillars and crown pillars in the shallow part of the A’er Hada Mine,and through on-site investigation,in-situ testing,laboratory experiments,theoretical analysis,and numerical simulation,this paper demonstrates a systematic study of the mining environment,the collaborative bearing of rock-backfill,the matching of surrounding rocks and support structures,residual ore recovering methods and stability.The main work and achievements are as follows:(1)On-site investigations were carried out on the distribution of residual ore and mine-out areas in the shallow part of the mine.The mechanical properties of the ore,surrounding rocks and backfill were tested,as well as the in-situ stress of the mine area.The joints and structures of the surrounding rock was analyzed,and surrounding rocks stabilities were classified.The distribution law of the stress field model in the mine area was established,and the mining conditions,stability of the mine-out areas,and the ground pressure problems faced during mining were also analyzed.All these works laid the foundation for residual ore recovering,backfilling,support design and optimizing,and mining stability control.(2)Aiming at the potential shear displacement problem that may occur at the interface between backfill and surrounding rocks during the residual ore recovering process,a shear displacement test method for the backfill-rock combination was designed.Combining with digital image technology and three-dimensional laser topography scanning technology,a three-dimensional modeling process for rough joint surfaces was established.The dynamic behavior and failure characteristics of the backfill-rock combination under shear displacement were studied based on the roughness of Barton curve and the free sheared surface.These works revealed mechanical damage mechanism of the heterogeneous of heterogeneous combination based on free joint surfaces,improved the existing shear theory of isomeric complex with rough joint surfaces,and provided a theoretical basis for preventing and control of backfill disasters in mines.(3)Directing at the dynamic disturbance on the backfill-rock collaborative bearing structure caused by blasting operation during the residual ore recovering,the Hopkinson impact test was carried out on the backfill-rock combination.The impact deformation law and energy distribution characteristics of the backfill-rock combination under different backfilling ratios,rock strengths,and impact pressures were analyzed.It was found that the stress-time curve of the combination presented a "double peak" mode under the impact load,and the combination’s temporal and spatial evolution of crack propagation and gradient failure were summarized with the help of high-speed camera.The synergistic deformation mechanism between backfill and surrounding rocks under dynamic load was elucidated,providing a scientific basis for blast design and stability control during residual ore recovering.(4)The typical failure modes of rock in the A’er Hada mine and the failure mechanism of support structures were investigated,and the bearing structure of surrounding rocks with different stability classification was calculated.Based on the division of shallow support layers,deep support layers,and key support layers,the design of support for different qualities of surrounding rocks was studied,and the influence mechanism of matching the quality of support structure and surrounding rocks on the mining stability was revealed through simulation analysis,and the optimal design of support parameters such as thickness of shotcrete and spacing of steel frames was completed.(5)Based on the analysis of residual ore occurrence and mining technology conditions,the mining design of the crown pillar and rib pillar ore in the shallow part of A’er Hada was carried out.Three collaborative bearing models during the recovering of residual ore were established:"backfill-pillar-backfill","rockbackfill-pillar",and"rock-backfill-rock".The impact of backfill strength and surrounding rock(ore pillar)quality on the stability of the collaborative bearing structure was systematically studied.The propagation and attenuation mechanisms of blasting vibration in different collaborative bearing structures were revealed through stress wave disturbance simulation.The above research revealed the dynamic and static loading impact on the stability of the mining pillars,surrounding rock,and backfill during the residual ore recovering,and provided scientific guidance for residual ore recovering design and safe recovering. |
