张年学, 盛祝平, 李守定. 2022. 崖腔型悬崖的稳定性估算[J]. 工程地质学报, 30(4): 1292-1303. doi: 10.13544/j.cnki.jeg.2021-0832.
    引用本文: 张年学, 盛祝平, 李守定. 2022. 崖腔型悬崖的稳定性估算[J]. 工程地质学报, 30(4): 1292-1303. doi: 10.13544/j.cnki.jeg.2021-0832.
    Zhang Nianxue, Sheng Zhuping, Li Shouding. 2022. Stability assessment of a hanging cliff[J]. Journal of Engineering Geology, 30(4): 1292-1303. doi: 10.13544/j.cnki.jeg.2021-0832.
    Citation: Zhang Nianxue, Sheng Zhuping, Li Shouding. 2022. Stability assessment of a hanging cliff[J]. Journal of Engineering Geology, 30(4): 1292-1303. doi: 10.13544/j.cnki.jeg.2021-0832.

    崖腔型悬崖的稳定性估算

    STABILITY ASSESSMENT OF A HANGING CLIFF

    • 摘要: 崖腔型悬崖破坏,是一种崩塌地质灾害,对线路工程与居住环境的安全性必须进行评估。假设张应力呈线性三角形分布,提出了一种评估崖腔型悬崖体稳定性的估算方法:首先计算张力矩,应用张力矩与压力矩相等的力矩平衡原理,计算出张力面上的总张力,然后按张力线性分布原理求出最大张应力。崖腔型悬崖的破坏是顶部最大张应力拉裂岩石而发生的。所以稳定系数定义为抗拉强度与最大张应力之比,用以评价崖腔型悬崖的稳定性。用算例讨论了影响崖腔型悬崖张应力大小的因素:悬崖体厚度H、岩石容重γ与崖腔深度L,分析了它们对不同厚度岩体与不同崖腔深度条件下最大张应力变化与破坏的一般变化规律,以及节理裂隙发育程度对岩体抗拉强度的影响,并提出了相关建议。算例表明本方法与悬臂梁的弹性力学解方法结果相差很大,证明弹性力学解对“深梁”型悬崖是不适用的。

       

      Abstract: Failure of a hanging cavity cliff is a rock fall geological hazard,which affects safety of road projects and housing environment. Therefore,it is critical to understand its stability and factors controlling its failures. We proposed an approach for assessing the rock mass stability of a hanging cavity cliff based on an assumption of a linear triangle distribution of the tensile stress along the wall. First,we calculated the tensile moment based on the moment balance among tensile and compression forces and in turn derived the total tensile force on the wall surface. Then we obtained the maximum tensile stress by using principle of the linear distribution of tensile stress along the wall. The failure of a hanging cavity cliff attributes to the tensile failure of rock at the top of the cliff when the maximum tensile stress exceeds the tensile strength of rock. To assess the stability of a hanging cliff,we calculated the safety factor as the ratio of the tensile strength and the maximum tensile stress. The result of the proposed approach is different from the solution for a cantilever beam from mechanics of elasticity,which demonstrates potential limitations of mechanics of elasticity in analysis of an overhanging cliff. We used a case study to assess factors that determined the magnitude of the tensile stress in a hanging cliff,including the thickness(height) H of the hanging cliff body,unit weight of rock(γ),and length(depth)(L) of the hanging cavity. The results show that the maximum resulting tensile stress is proportional to L and φ,but inversely proportional to H. A deeper/longer wall tends to have a greater possibility of tensile failure than a shallower/shorter one. As the tensile stress decreases when the wall becomes thicker,the shear failure becomes more likely than the tensile failure for a thicker wall. We also made recommendations for future studies and its applications in engineering projects and prevention of geological hazards.

       

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