考虑围压影响的深埋圆隧围岩应变软化与剪胀特性分析
发布时间：2018-08-30 20:23
【摘要】：不同围压下岩石应变软化与剪胀特性不同,若在隧洞开挖中考虑围岩塑性区域内变化围压影响,其应力 应变场求解方式将区别于既有文献中的传统方法。根据围压影响下应变软化围岩的临界塑性剪切应变变化特征,给出改进的判断围岩是否进入塑性残余区域的规则;引入考虑围压与临界塑性剪切应变的非线性剪胀模型。基于Hoek-Brown屈服准则,根据一定径向应力增量将围岩塑性软化与残余区域分层,采用有限差分法对围岩应力 应变场进行求解;为分析围压对围岩稳定性的影响,根据临界塑性剪切应变与剪胀系数变化与否,设定4种非线性力学模型,深入分析并比较4种力学模型下临界塑性剪切应变、剪胀系数与围岩变形等在塑性软化与残余区域的分布规律。研究结果表明:地质强度指标GSI较小时,考虑围压影响下的围岩应力 应变场与未考虑时差异明显;此时临界塑性剪切应变的减小对开挖边界的围岩剪胀性具一定抑制作用。
[Abstract]:The characteristics of strain softening and shear expansion of rock under different confining pressures are different. If the influence of variation of confining pressure in the plastic region of surrounding rock is taken into account in tunnel excavation, the stress and strain field solution will be different from the traditional method in the existing literature. According to the variation characteristics of critical plastic shear strain of strain-softening surrounding rock under the influence of confining pressure, an improved rule to judge whether the surrounding rock enters into plastic residual region is given, and a nonlinear shear-expansion model considering confining pressure and critical plastic shear strain is introduced. Based on the Hoek-Brown yield criterion, the plastic softening and residual zone of surrounding rock are stratified by a certain radial stress increment, and the stress and strain field of surrounding rock is solved by finite difference method, in order to analyze the influence of confining pressure on the stability of surrounding rock. According to the change of critical plastic shear strain and shear expansion coefficient, four kinds of nonlinear mechanical models are set up, and the critical plastic shear strain under four kinds of mechanical models is analyzed and compared. Distribution of shear expansion coefficient and surrounding rock deformation in plastic softening and residual region. The results show that the stress and strain field of surrounding rock under the influence of confining pressure is obviously different from that without considering the geological strength index GSI, and the decrease of critical plastic shear strain can restrain the shear dilatancy of surrounding rock at the excavation boundary to some extent.
【作者单位】： 华中科技大学岩土与地下工程研究所;
【基金】：新世纪优秀人才支持计划资助项目(NCET 06 619)
【分类号】：U451.2
[Abstract]:The characteristics of strain softening and shear expansion of rock under different confining pressures are different. If the influence of variation of confining pressure in the plastic region of surrounding rock is taken into account in tunnel excavation, the stress and strain field solution will be different from the traditional method in the existing literature. According to the variation characteristics of critical plastic shear strain of strain-softening surrounding rock under the influence of confining pressure, an improved rule to judge whether the surrounding rock enters into plastic residual region is given, and a nonlinear shear-expansion model considering confining pressure and critical plastic shear strain is introduced. Based on the Hoek-Brown yield criterion, the plastic softening and residual zone of surrounding rock are stratified by a certain radial stress increment, and the stress and strain field of surrounding rock is solved by finite difference method, in order to analyze the influence of confining pressure on the stability of surrounding rock. According to the change of critical plastic shear strain and shear expansion coefficient, four kinds of nonlinear mechanical models are set up, and the critical plastic shear strain under four kinds of mechanical models is analyzed and compared. Distribution of shear expansion coefficient and surrounding rock deformation in plastic softening and residual region. The results show that the stress and strain field of surrounding rock under the influence of confining pressure is obviously different from that without considering the geological strength index GSI, and the decrease of critical plastic shear strain can restrain the shear dilatancy of surrounding rock at the excavation boundary to some extent.
【作者单位】： 华中科技大学岩土与地下工程研究所;
【基金】：新世纪优秀人才支持计划资助项目(NCET 06 619)
【分类号】：U451.2
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