Mechanism of connected instability of “rib-roof” in deep large section chamber under dynamic disturbance

Dynamic disturbance induced surrounding rock failure and instability of deep large-section chamber is a prominent problem in large modern coal mines. Based on geological conditions of the typical large-section chamber for coal gangue separation in Xinjulong Coal mine,firstly,this paper studies the deformation and failure evolution process of the surrounding rock of the typical large-section chamber under the dynamic disturbance coupling high static stress using the FLAC3D simulation software,and then reveals the mechanism of connected instability of “rib-roof” in deep large section chamber under dynamic disturbance. Finally,an integrated multi-level security control strategy is proposed. The results indicate that:① during dynamic disturbance,the "slab-rent structure " in the limit equilibrium area of the deep large-section chamber rib was first broken,and then the caving or roof fall of anchorage roof was activated and finally instability of deep large-section chamber was ultimately manifested. ② Dynamic disturbance is the inducing factor of surrounding rock instability of deep large-section chamber,and the high static stress in the limit equilibrium zone is the basic force source. ③ The prevention of surrounding rock instability induced by dynamic disturbance should integrate weakening dynamic load and strengthening anchorage bearing capacity together. For this reason,an multi-level security control strategy integrated the"Stress wave elimination and energy absorption in deep part of chamber-full section anchorage support in shallow part-flexible protection on chamber sufure". The results show that after adopting this technology,the instability of deep large-section chamber was restrained,and the volume of the plastic zone is reduced by 18.46% and the deformation of surrounding rock decrease and the decreasing amplitude is up to 31.78%.