Stability Analysis and the Stabilisation of Flexural Toppling Failure
Stability Analysis and the Stabilisation of Flexural Toppling Failure
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DOI：
10.1007/s00603-008-0020-2
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发表时间：
2009-10
影响因子：
6.2
通讯作者：
M. Amini;A. Majdi;Ö. Aydan
中科院分区：
文献类型：
--
作者：
M. Amini;A. Majdi;Ö. Aydan
弯曲倾倒是一种破坏模式，可能发生在岩石边坡和大型地下开挖的大范围层状岩层中。当岩体由一组平行结构面陡倾斜于开挖面时，岩体也会有弯曲倾倒破坏的可能。在这种情况下，岩体的行为就像倾斜叠加的悬臂梁，在自身重量的作用下弯曲，同时将荷载传递给下伏地层。当弯曲应力超过岩柱抗拉强度时，将引发弯曲倾倒破坏。由于岩柱是“静态不确定的”，因此，它们的安全系数可能不仅仅由平衡方程决定。本文描述了具有弯曲顶顶破坏可能性的倾斜叠加悬臂岩柱序列的解析模型。该模型基于相容方程原理，提出了一种确定柱间力大小和施加点的新方法。在此模型的基础上，可以独立计算每根岩柱的安全系数。因此，每个岩柱都有一个独特的安全系数。选取任意岩柱中存在的最小安全系数作为岩体代表性安全系数，在此基础上提出了简单的方程，用于保守岩体稳定性分析与设计。建立了一些新的关系，为该岩体稳定设计全注浆锚杆的长度、截面积和形态提供了理论依据。最后，将新提出的方程与现有的弯曲倾倒破坏实验模型（基础摩擦和离心试验）的结果进行了比较，以进一步验证。
Flexural toppling is a mode of failure that may occur in a wide range of layered rock strata in both rock slopes and large underground excavations. Whenever rock mass is composed of a set of parallel discontinuities dipping steeply against the excavated face plane, the rock mass will have the potential of flexural toppling failure as well. In such cases, the rock mass behaves like inclined superimposed cantilever beams that bend under their own weight while transferring the load to the underlying strata. If the bending stress exceeds the rock column’s tensile strength, flexural toppling failure will be initiated. Since the rock columns are “statically indeterminate,” thus, their factors of safety may not be determined solely by equations of equilibrium. The paper describes an analytical model with a sequence of inclined superimposed cantilever rock columns with a potential of flexural topping failure. The model is based on the principle of compatibility equations and leads to a new method by which the magnitudes and points of application of intercolumn forces are determined. On the basis of the proposed model, a safety factor for each rock column can be computed independently. Hence, every rock column will have a unique factor of safety. The least factor of safety that exists in any rock column is selected as the rock mass representative safety factor based on which simple equations are proposed for a conservative rock mass stability analysis and design. As a result, some new relations are established in order to design the length, cross-sectional area and pattern of fully grouted rock bolts for the stabilisation of such rock mass. Finally, the newly proposed equations are compared with the results of existing experimental flexural toppling failure models (base friction and centrifuge tests) for further verification.