Three-dimensional roof collapse analysis in circular tunnels in rock
Three-dimensional roof collapse analysis in circular tunnels in rock
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DOI：
10.1016/j.ijrmms.2020.104275
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发表时间：
2020-04-01
影响因子：
7.2
通讯作者：
Michalowski, Radoslaw L.
中科院分区：
文献类型：
--
作者：
Park, Dowon;Michalowski, Radoslaw L.
分析了圆形断面隧道顶板的倒塌。采用极限分析的运动学方法，并通过 Hoek-Brown 破坏准则描述岩石的强度。 Hoek-Brown 函数的参数形式用于避免引入剪切强度准则的替代显式形式。考虑三个安全措施：稳定数、安全系数以及确保顶板稳定性所需的支撑压力。破坏机制中岩块的形状由具有分段线性母线的直立椭圆锥体和插入两半锥体之间的棱柱形截面组成。隧道块体横截面的复杂性使得耗散功和外力功的速率错综复杂地结合在一起。所有三种安全措施都强烈依赖于地质强度指数中描述的岩石质量，而对系数 mi 中捕获的岩石类型的依赖则不太明显。顶板破坏机制的长度受到取决于隧道中支撑肋的间距的约束。所有安全（或稳定性）衡量标准都明显取决于长度限制；肋骨之间的间距越短，隧道抵御顶板塌陷的安全性就越高。二维分析产生最保守的结果。
Collapse of a roof in circular cross-section tunnels is analyzed. The kinematic approach of limit analysis is utilized, with strength of the rock described by the Hoek-Brown failure criterion. The parametric form of the Hoek-Brown function is used to avoid introduction of an alternative explicit form of the shear strength criterion. Three measures of safety are considered: stability number, the factor of safety, and the support pressure needed to assure roof stability. The shape of the rock block in the failure mechanism consists of a right elliptic cone with a piece-wise linear generatrix and a prismatic section inserted between the two halves of the cone. The complexity of the cross-section of the block with the tunnel makes for an intricate integration of the rates of the dissipated work and the work of external forces. All three measures of safety are strongly dependent on the quality of rock described in the Geological Strength Index, whereas the dependence on the rock type captured in coefficient mi is less distinct. The length of the roof failure mechanism is subject to a constraint dependent on the spacing of the supporting ribs in the tunnel. All measures of safety (or stability) are distinctly dependent on the length constraint; the shorter the spacing between the ribs, the safer the tunnel against roof collapse. The 2D analysis yields the most conservative outcome.