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To address the inadequate understanding of the fracturing behavior of thick-hard strata and the collapse-movement mechanism of overlying strata in 10 m ultra-large mining height faces of extra-thick coal seams, this study took the 122104 working face of Caojiatan Coal Mine as the engineering background. A combined approach involving physical similarity simulation, image processing with statistical analysis, and field monitoring was adopted to investigate the dominant role of thick-hard strata breakage in the overburden collapse and movement process. The engineering applicability and consistency of the model results were verified with field measurements. (1) An automatic fracture extraction and multi-index quantification method based on multi-temporal overburden images was proposed, enabling efficient quantification of parameters such as fracture development height, coverage area, and total length. The results show that the fracture parameters exhibit a pronounced "step-like" jump evolution with face advance, where each abrupt change strictly corresponds to the breakage sequence of specific thick-hard strata (I, II, and III). This quantitatively reveals, from the perspective of fracture evolution, the controlling effect of thick-hard strata breakage on overburden movement. (2) The breakage mechanism of thick-hard strata is characterized as a "cantilever beam-coordinated collapse" process. Before breakage, thick-hard strata form a large-span cantilever beam structure that constrains overburden collapse; when the cantilever reaches its limit, sudden breakage occurs, triggering large-scale coordinated collapse of the overburden, demonstrating typical structural failure characteristics. (3) Field monitoring data, including layered subsidence, mine pressure, and microseismicity, provide effective mutual validation with the model experiments. The coordinated movement mode of strata revealed by the layered subsidence curves aligns well with the "step-like" propagation pattern of fractures observed in the model; mine pressure monitoring indicates that the breakage of thick-hard strata II and III directly induces intense periodic weighting; microseismic monitoring further confirms that the periodic breakage of thick-hard strata constitutes the main source of concentrated energy release in the overburden. These results jointly verify, in terms of spatial evolution and energy release, the field applicability of the mechanism by which thick-hard strata breakage dominates overburden movement. From the perspective of fracture evolution, this study systematically elucidates the mechanism of thick-hard strata breakage-dominated overburden collapse and movement under ultra-large mining height conditions, providing a quantitative theoretical basis for improving overburden movement theory and preventing roof disasters in 10 m ultra-large mining height faces.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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