Research on the Bearing Structure Movement of Overburden Strata in Stope under Thick Sandstone Conditions and Its Energy Accumulation and Dissipation Evolution Characteristics

Abstract

In response to the complex occurrence of coal bearing strata leading to severe overburden strata instability and mining pressure, especially the instability of thick sandstone roof causing strong dynamic pressure disasters, threatening operational safety, and causing surface damage. This article takes the fully mechanized coal mining face with thick sandstone conditions in the western mining area of Inner Mongolia as the research object, and uses a combination of physical model experiments and numerical simulation analysis to explore the movement characteristics and energy accumulation and dispersion evolution relationship of the overlying strata bearing structure in the mining area. The study found that the overlying strata in the mining area exhibit a progressive instability process from bottom to top, characterized by the "thick sandstone roof hanging-breaking-instability" during the working face mining. The deformation of the thick sandstone roof is not obvious before it breaks, and it quickly becomes unstable after reaching the bearing limit. It is necessary to strengthen prediction and technical treatment; The energy accumulation at the ends and middle of the exposed area before the rupture is significant, and the accumulation amount is positively correlated with the unstable dynamic load intensity. At the moment of rupture, the energy is released and converted into unstable kinetic energy, and at the same time, it reaccumulates at the exposed part of the overlying high-level thick sandstone roof. Under the same conditions, the unstable kinetic energy of the low position thick sandstone roof has a shorter transmission distance and smaller loss, resulting in more significant impact on the direct roof and support of the working face. The kinetic energy of the high position thick sandstone roof decays significantly, and the impact of strong dynamic pressure on disasters needs to be analyzed in conjunction with specific rock conditions and load transfer. This study reveals the laws of overlying rock movement and energy evolution in thick sandstone mining conditions, providing a scientific basis for the identification and treatment of strong dynamic pressure disasters in coal mining faces.