The retained coal in the end slope of an open-pit mine can be mined by the highwall mining techniques. However, the instability mechanism of the reserved rib pillar under dynamic loads of mining haul trucks and static loads of the overlying strata is not clear, which restricts the safe and efficient application of highwall mining. In this study, the load-bearing model of the rib pillar in highwall mining was established, the cusp catastrophe theory and the safety coefficient of the rib pillar were considered, and the criterion equations of the rib pillar stability were proposed. Based on the limit equilibrium theory, the limit stress of the rib pillar was analyzed, and the calculation equations of plastic zone width of the rib pillar in highwall mining were obtained. Based on the Winkler foundation beam theory, the elastic foundation beam model composed of the rib pillar and roof under the highwall mining was established, and the calculation equations for the compression of the rib pillar under dynamic and static loads were developed. The results showed that with the increase of the rib pillar width, the total compression of the rib pillar under dynamic and static loads decreases nonlinearly, and the compression of the rib pillar caused by static loads of the overlying strata and trucks has a decisive role. Numerical simulation and theoretical calculation were also performed in this study. In the numerical simulation, the coal seam with a buried depth of 122 m and a thickness of 3 m is mined by highwall mining techniques. According to the established rib pillar instability model of the highwall mining system, it is found that when the mining opening width is 3 m, the reasonable width of the rib pillar is at least 1.3 m, and the safety factor of the rib pillar is 1.3. The numerical simulation results are in good agreement with the results of theoretical calculation, which verifies the feasibility of the theoretical analysis of the rib pillar stability. This research provides a reference for the stability analysis of rib pillars under highwall mining.

露天矿端坡的残煤可采用高壁开采技术开采。然而，预留肋柱在矿用运输车动载和上覆地层静载作用下的失稳机理尚不明确，制约了高壁开采的安全高效应用。本研究建立了高壁开采肋柱的承载模型，考虑了尖头突变理论和肋柱的安全系数，提出了肋柱稳定性的判据方程。基于极限平衡理论，分析了肋柱的极限应力，得到了高壁开采肋柱塑性区宽度的计算公式。基于Winkler基础梁理论，建立了高壁采下肋柱与顶板组成的弹性地基梁模型，建立了肋柱在动静荷载作用下受压的计算方程。结果表明，随着肋柱宽度的增加，肋柱在动静荷载作用下的总受压非线性减小，而上覆地层和卡车静载引起的肋柱受压具有决定性作用。本研究还进行了数值模拟和理论计算。在数值模拟中，采用高壁开采技术开采埋深122 m、厚度3 m的煤层。根据建立的高壁开采系统肋柱失稳模型，研究发现，当采口宽度为3 m时，肋柱合理宽度至少为1.3 m，肋柱安全系数为1.3。数值模拟结果与理论计算结果吻合较好，验证了肋柱稳定性理论分析的可行性。该研究为高壁开采下肋柱稳定性分析提供参考。