Roof stability analysis of deeply-buried cavities based on nonlinear Baker criterion
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摘要: 针对Hoek-Brown和Mohr-Coulomb准则主要分别适用于岩体和土体的情形,采用更具适用性的广义非线性Baker准则,并结合极限分析上限方法,旨在研究深埋硐室拱顶岩土体的动力稳定性。通过构建满足Baker准则下拱顶塌落的曲线型破坏机构,考虑竖向地震荷载的影响,计算内外力功率并建立功率平衡方程,基于变分原理推导在有无竖向地震力作用时拱顶破坏机制的上限表达式,从而求解得到破坏面形状、塌落拱高度和宽度的解析解。同时采用ABAQUS数值模拟验证解析解的有效性及合理性,研究分析不同参数下拱顶破坏机制的变化规律。结果表明除岩土体特性参数外,尤其是向上的竖向地震力对拱顶破坏范围有显著影响。
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关键词:
- 深埋硐室 /
- 拱顶稳定性 /
- 非线性Baker准则 /
- 竖向地震力 /
- 上限分析
Abstract: The dynamic roof stability analysis of deeply-buried cavities is investigated by using the upper bound limit analysis method adopting a more general nonlinear Baker criterion, in contrast to the Hoek-Brown and Mohr-Coulomb criteria which are mainly applicable to rock and soil, respectively. A curved failure mechanism for roof collapse is proposed in the realm of the Baker criterion. The vertical seismic loading is considered herein. The balance equation for work rate is then established after computing the external and internal rates of work. Based on the variational principle, the upper-bound formulation for roof collapse mechanism is derived with/without considerations of the vertical earthquake effects. Accordingly, the closed-form solutions for the failure surface, collapse height and width are explicitly obtained. At the same time, the ABAQUS modelling is used to verify the robustness and validity of closed-form solutions. The parametric studies are carried out to investigate the change laws of the roof collapse mechanism under different parameters. The results indicate that apart from rock/soil properties, the upward seismic force has a significant effect on the failure region above the cavity roof. -
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表 1 有限元模型几何参数
Table 1 Geometric parameters of finite element model
H/m B/m H0/m Lc/m 40 50 5 10 表 2 不同破坏准则下的岩土体参数值
Table 2 Rock/soil parameters under different failure criteria
γ/
(kN·m-3)Baker强度参数 HB强度参数 MC强度 A n T pa/
kPaA B σt/
kPaσc/
kPac/
kPaϕ/
(°)25 2.08 0.7 0.3 100 0.75 0.7 30 3000 115 51.6 表 3 隧道围岩力学参数
Table 3 Mechanical parameters of surrounding rock of tunnel
γ/(kN·m-3) c/kPa ϕ/(°) A n T 18 30 24 0.45 0.7 0.67 表 4 围岩压力结果对比
Table 4 Comparative results of pressure of surrounding rock
监测点桩号 埋深/
m本文结果/kPa 规范计算结果/
kPa误差/
%ZK3+610 41.41 118.63 113.66 4.4 -
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