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Author: Admin | 2025-04-27
Rib pillar widths can be obtained, and the calculation results are shown in Figs. 16 and 17.Fig. 16Ultimate stress of the rib pillar under the No. 1 haulage benchFull size imageFig. 17Safety factor of the rib pillar under the No. 1 haulage benchFull size imageAs shown in Figs. 16 and 17, with the increase of the rib pillar width, the ultimate stress of the rib pillar under the No. 1 haulage bench approximately decreases linearly, and the safety factor of the rib pillar approximately increases linearly. When the rib pillar width Wp increases from 0.54 to 3.00 m, the ultimate stress of the rib pillar gradually decreases from 11.965 to 11.733 MPa, and the safety factor of the rib pillar increases from 0.66 to 2.21. The ultimate stress of the rib pillar decreases slightly, with a reduced rate of 1.9%, indicating that the ultimate stress is less affected by the change of the rib pillar width. The safety factor of the rib pillar increases greatly, with a growth rate of 234.8%, which is greatly affected by the change of the rib pillar width.4.4 Analysis on reasonable reserved width of the rib pillarCombined with Figs. 15 and 17, the criterion value Δ of the rib pillar under the No. 1 haulage bench and statistical chart of the safety factor f can be obtained. According to the crust catastrophe instability model of rib pillars in highwall mining, if the rib pillar remains stable, criteria value Δ > 0 is required. When the safety factor of the rib pillar f > 1.3 is taken, Eq. (37) can be obtained by solving the simultaneous equations of Eq. (19), Eq. (23), Eq. (24) and Eq. (25):$$W_{{\text{p}}} > 1.269{\, }{\text{ m}}$$ (37) Based on the above calculation, the rib pillar width under the No. 1 haulage
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