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To investigate the instability and deformation characteristics of thick hard roofs overlying open roadways in deep mines, this study employs the sixth mining area of Dongtan Coal Mine(Yanzhou mining district)as an engineering case. A Timoshenko beam model on an elastic foundation was established to characterize roof deflection, incorporating structural and mechanical properties of thick hard strata. Analytical solutions for bending moment, shear force, and deflection were derived, revealing significant influences of roof layer position, thickness, and strength on roadway deformation-validated through numerical simulations. Key findings include: ① Roof flexural fracturing is critically controlled by thick hard roof properties. Maximum subsidence and fracture dimensions exhibit negative correlations with roof layer elevation: each 5 m elevation increase reduces subsidence by 16%-37%. Lower-layer roofs develop fractures deeper within coal walls, generating larger fractured blocks. The influence of roof thickness and strength evolves through two stages: During initial roadway development, thick hard roofs form stable, high-capacity cantilever structures where subsidence negatively correlates with thickness/strength. Subsequent intense mining triggers cantilever fracture, releasing dynamic loads that dominate roadway deformation. At this stage, thickness and strength positively influence fracture dimensions and energy release, intensifying roadway destabilization. ② Roadway deformation progresses through static load-dominated and dynamic load-expansion stages. Initially, the cantilever transfers static loads to deeper coal, expanding plastic zones. Post-fracture, the absence of immediate roof buffering allows dynamic stress waves to directly intensify surrounding rock damage. ③ Field tests demonstrate that hydraulic fracturing combined with deep-hole blasting reduces dynamic impact energy by 60%. Integrated with high-preload anchor cables and grouting, this limits roof subsidence to <300 mm. Optimizing advance rates to 3 m/day reduces high-energy seismic events by 65%. This research elucidates the mechanical mechanisms of impact-induced failure beneath thick hard roofs and proposes a targeted control strategy integrating directional roof cutting, multi-level support, and advance rate optimization. The outcomes provide theoretical and technical foundations for roadway stability control in deep mining environments under thick, hard, directly overlying strata.
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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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