Study on deformation characteristics and support technology of cross layer roadway under the influence of goaf

Aiming at the problem that the surrounding rock of the advancing roadway at the east wing of -550 m level is not easy to be stable when the tunnel is advanced in a short distance under goaf in Liangbei Mine, the stress distribution law and deformation characteristics of the goaf and coal pillar formed by two adjacent working faces at different times on the surrounding rock near the advancing roadway were analyzed by numerical simulation. Based on the support principle of multi-level coupling bearing structure, the corresponding deformation control countermeasures and support schemes were proposed and applied in the field. The results show that with the advance of the working face, the stress recovery zone of the raw rock of the floor strata in the goaf diffuses from the middle of the goaf to the surrounding areas, and the plastic failure zone is distributed in an “inverted saddle” shape; under the influence of the stress produced by the disturbance process of progressive compaction of the adjacent unstable goaf and the stress concentration of the coal pillar, the plastic failure zone of the tunnel is asymmetrically distributed; based on the zoning characteristics of broken zone, plastic zone and elastic zone formed by the failure of roadway surrounding rock, the supporting strategy of making full use of internal and external support to form multi-level coupled bearing structure is put forward. The multi-level coupling control technology of “high strength anchor-mesh-cable + reinforcement of shallow and deep surrounding rock by staged grouting + shotcreting” in shallow and deep surrounding rocks has achieved good application results in the field.