Abstract:To investigate the reasonable roof-contacted filling rate (RCFR) of the backfill in the goaf of a deep mine, the three-hinged arch mechanics model was applied to the two-step mine, and the stress expressions of the goaf roof with different roof-contacted filling rates were derived. Then, the influence of RCFR on the stress state of the roof was analyzed combined with numerical simulation. The results indicated that vertical stress changed the stress state of the roof in the room-stopes and pillar-stopes, while horizontal stress mainly affected the stress state of the roof in the room-stopes. The RCFR in the room-stopes had a greater influence on the formation of the self-stable arch of the roof in pillar-stopes. During the mining process of the Dongguashan Copper Mine, the actual RCFR at the site was about 80%, which achieved a safe and stable uninterrupted recovery of mineral resources.

Key words: arch mechanical model; roof-contacted filling rate; roof stability; numerical simulation; two-step mining