Control mechanism of the surrounding rock structure of multisection stopes in steeply dipping coal seams under overburden transient changes excitation.

Abstract

The mining cycle of multi-section stopes in steeply dipping coal seams is protracted, and the ground pressure appearance is complex.This study utilized physical simulation and theoretical analysis to investigate the surrounding rock structural evolution mechanism in multi-section longwall stopes of steeply dipping coal seams, the mechanical response of barrier pillars under the transient change excitation of the overburden spatial structure, and determine the key dimensions of barrier pillars for controlling the surrounding rock structure. These findings indicate that the movement and structural evolution of the surrounding rock in multi-section stopes of steeply dipping coal seams are governed by the stability of the barrier pillars. Transient changes in the overburden structure have been demonstrated to induce alterations in the static and dynamic mechanical responses of the barrier pillars.The instantaneous maximum abutment pressure, which is formed by the dynamic and static superimposed loads on the barrier pillar, can be calculated through the establishment of a mechanical model based on the overburden structure of the gob prior to and following the transient. By taking the instantaneous maximum abutment pressure as the static load, the critical width and yield critical width of the barrier pillar can be obtained.