岩石边坡倾倒破坏之块体倾倒(Block Toppling)数据集
1 引言
倾倒破坏(Toppling Failure) 这个词最初是由是Goodman and Bray在上世纪70年代提出, 意指一组平行节理的岩体朝着边坡方向发生的倾倒破坏。按照Goodman and Bray(1976)的分类, 倾倒破坏可以分为三种形式: (a) 块体倾倒(Block Toppling); (b) 屈曲倾倒(Flexural toppling); (c) 块体屈曲倾倒(Block flexure toppling). 如下图所示.
过去的公 众 号文章中多次讨论过倾倒破坏, 参看如下的链接.
屈曲倾倒破坏(flexural toppling failure)
岩土边坡的破坏类型(C3)(Failure types of slope)
除了上面所述的三种倾倒模式外, Wyllie and Mah(2004)也讨论过另一种倾倒模式,称之为次倾倒模型(Secondary toppling modes). 这种破坏模式主要由岩石风化以及人类活动引起. 最典型的情形是坡脚开挖引起边坡上部岩体发生倾倒破坏, 如下图(d)所示. 这种现象在修建山区高速公路时经常遇到, 特别是出现在水平层理的砂岩和页岩中.
2 倾倒破坏的分析方法
按照Goodman and Bray(1976)的分析, 倾倒破坏必须满足下面的条件:
其中,
---边坡面的倾角(Dip of slope face);
---不连续岩体的内摩擦角(Internal friction angle of plane/joint);
---不连续岩体的倾角(Dip of plane/joint)
如果不连续面倾到边坡面并且其走向小于30度, 那么就有可能倾倒破坏, 这可以使用赤平极射投影方法来求解, 如上图(e)所示. 一个更专业的求解方法是使用DIPS软件. 在此基础上, Rocscience发展了一个基于静力平衡的倾倒破坏分析软件RocTopple. 倾倒破坏最先进的分析方法是由Cundall提出的离散元法, 目前这样的分析方法有: UDEC，3DEC, PFC, Slope Model等。
3 块体倾倒数据集
在过去, 已经发展出一个屈曲倾倒数据集"flexural toppling failure", 在此基础上发展出目前的块体倾倒"Block Toppling"数据集. 这个数据集的内容主要包括在下面两个数据集中:
(1)\Step-Path-Failure(Discontinuity Persistence)
(2) \lattice spring model
进一步的优化还在进行之中.
4 参考文献
[1] Duncan C. Wyllie (2018) Rock Slope Engineering Civil Applications. Fifth Edition. 621p. (pdf)
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[4] Alejano, L. R., et al. (2018). "Block toppling stability in the case of rock blocks with rounded edges." Engineering Geology 234: 192-203.
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[13] Lanaro, F., et al. (1997). D.E.M. modelling of laboratory tests of block toppling. International Journal of Rock Mechanics and Mining Sciences. 34: 173.e171-173.e115.
[14] Scavia, C., et al. (1990). "Probabilistic Stability Analysis of Block Toppling Failure in Rock Slopes." International Journal of Rock Mechanics and Mining Sciences 27(6): 465-478.
[15] Wyllie, D. C. 1980. Toppling Rock Slope Failures, Examples of Analysis and Stabilization. Rock Mechanics, Vol.13, pp.89–98.
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