Research on power instability of surrounding rock and optimization strategy of anti-impact support for thick coal bed roadway

Focusing on the problem of dynamic instability of the surrounding rock in the roadway of thick coal seam, by combining the theory of elasticity mechanics and the principle of impact dynamics, the propagation mechanism of the dynamic loaded stress wave and the dynamic response law of the supporting structure are investigated, and the optimization scheme of the anti-impact support for the surrounding rock in the roadway is put forward. The study shows that: the propagation of dynamic loaded stress wave goes through the initial stress disturbance stage, the main stress fluctuation stage, and the stress field reconstruction stage in three stages of the evolution process; the progressive damage of anchorage components occurs in the fluctuation propagation stage, and the support system enters into the stable state of energy dissipation in the stress equilibrium stage; the parameters of the movement of peripheral rock mass points and the impact intensity show a non-linear growth relationship; 10⁵ J is established as the critical threshold of peripheral rock dynamic instability, and the impact of the over-limit will trigger the failure of the support system; the full-loaded stress wave propagation mechanism and dynamic response law of the support structure are investigated. The support system failure is triggered by the over-limit impact; the full-section anchor cable gradient energy release support system can improve the equivalent stiffness of the roof bearing layer and reduce the dynamic damage rate of the anchor cable by constructing the deep and shallow coordinated bearing structure; the depth of the perimeter rock fissure expansion is reduced by 60.1%～64.2% after the implementation of the optimized scheme, the convergent deformation is reduced by 49.8%～67.7%, and the integrity of the support structure is improved by 2.3 times.