Research on the Response Mechanism of Overlying Strata Failure and Ground Fissures Development Under High-Intensity Mining

Mining-induced ground fissures in the Ordos Basin pose critical threats to coal mine safety and ecological stability. This study integrated multi-source monitoring data (improves data acquisition efficiency by 60%) with theoretical models to elucidate the dynamic response mechanism between overlying strata failure and ground fissure development. The results demonstrate that: (1) Two rock beam structural models for initial and periodic fracturing of thick, hard rock strata are established, demonstrating that both failure modes are dominated by tensile–shear mechanisms. (2) Ground fissures exhibit distinct zonal characteristics, displaying a gradient pattern of “strong disturbance in the near field and weak response in the far field.” Quantitative data support this pattern: average fissure density is 36/hm², with a maximum of 45/hm² recorded in the immediate vicinity of the working face, declining steadily outward. (3) Overlying strata failure forms three distinct zones—caving zone (42 m), fissure zone (158 m), and longitudinal penetrating zone—reflecting the heterogeneous fracture characteristics of medium-hard rock strata under mining influence. (3) The proposed “virtual main arch—virtual auxiliary arch” equivalent support system theory elucidates the mechanistic differences between step fissures (attributed to local support system instability) and collapse fissures (driven by global support system instability) from a mechanical perspective. The developed chain response theory fills a critical theoretical gap and provides a novel method for predicting and preventing geological disasters in mining areas.