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Main roof mechanics model of non-pillar stope of EFARC in inclined coal seam (Part (I) The main roof mechanical model. Part (II) The main roof support conditions and the plane stress diagram)
Source publication
During the process of coal mining, there is a violent appearance of mining stress when the initial weighting occurs. To guarantee the safety of the gob-side entry formed automatically by roof-cutting (EFARC) in an inclined coal seam, a study was conducted on the initial weighting mechanism and appearance characteristics through field monitoring and...
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Citations
... In the mining of steeply dipping coal seams, due to the gravity dip effect, the roof strata not only move in the direction of vertical rock layers (similar to horizontal coal seam mining), but also move in the direction of parallel rock layers, resulting in a "temporal" and "asymmetric" deformation and failure process of the roof (Xie 2023;Xie et al. 2018;Wu 2024;Wang et al. 2015). Numerous scholars have adopted methods such as physical simulation experiments, theoretical analysis, numerical calculations, and on-site measurements to study the asymmetric deformation and failure motion laws of overlying strata with steeply dipping and high mining heights from different perspectives (Tu 2014;Xie et al. 2023a, b, c, d;Chai et al. 2019;Zhen et al. 2023), the distribution characteristics and distribution patterns of surrounding rock stress (Xie 2023;Luo et al. 2022a, b;Pang 2020), and the stability control mechanism of the "support surrounding rock" system (Xie 2021;Yang et al. 2020;Wang 2017;Xie et al. 2023a, b, c, d) Research and exploration have been carried out on the formation mechanism of surrounding rock disasters in working faces such as coal wall fragmentation Yang et al. 2019) and floor sliding , and targeted prevention and control measures have been proposed, which has promoted the continuous progress of theory and technology in mining steeply dipping coal seams and laid the foundation for further research. However, the spatial fracture evolution characteristics and fracture mechanism of overlying strata in steeply dipping and high mining areas are not yet clear. ...
To study the fracture instability characteristics and fracture mechanism of overlying strata in steeply dipping and large mining height stope, through the combination of physical simulation experiment, numerical calculation, theoretical analysis and field measurement, the correlation between the evolution of mining stress field and the fracture of overlying strata in large mining height stope under the effect of dip angle is analyzed, and the stress transfer path and the fracture mechanism of overlying strata are revealed. Finally, the influence mechanism of key strata on the evolution of the mining stress field of overlying strata is explained. The research shows that under the influence of gravity dip angle effect and mining height increase, the mining stress is non-equilibrium transferred and evolved in space, and the principal stress field presents the characteristics of partition evolution. The fracture trajectory of rock strata is multi-step and “八” shaped, and the inclined masonry structure and multi-step key strata form a cooperative bearing structure. The key layer of the ladder is the stress transmission structure between the caving zone and the stress arch, and the high stress in the overhanging area under the main roof is transmitted to the advanced roof. With the increase of dip angle, the height of the caving zone decreases, and the fracture range of ladder and principal stress arch decreases. The cracks in the middle and upper broken rock blocks increase, and the instability of the “high ladder rock layer” is easy to induce the simultaneous fracture of the “inclined masonry structure”, resulting in regional unbalanced instability and impact. The research results can provide some reference and guiding significance for the stability control of surrounding rock in longwall stope with steeply dipping.
