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基于四阶段应力-应变模型的深部巷道围岩弹塑性分析

Elastic-plastic analysis of surrounding rock in deep roadway based on four-stage stress-strain model

  • 摘要: 为分析巷道破裂区范围,基于统一强度准则和非关联流动法则,考虑中间主应力及扩容系数的影响,建立了深部巷道围岩弹性区-塑性区-软化区-破裂区四阶段应力-应变模型,并求得围岩应力、应变及变形的封闭解。结合工程案例,分析了不同强度参数、应力-应变模型、剪胀角、残余黏聚力等对围岩状态变化的影响。研究结果表明:强度参数对围岩应力、应变及峰后破坏范围均具有重要影响。随着强度参数的不断增加,围岩环向应力峰值及峰后破坏范围均不同程度增大,应力曲线左移;扩容系数与强度参数和剪胀角均成正相关关系;随着残余黏聚力的不断增加,围岩峰后破坏范围及表面位移均呈现出非线性减小特征,其减小速率不断降低;与其他应力-应变模型相比,围岩峰后破坏区位移呈现出EBM>EPBM>ESM>本文模型>EPM的变化特征。此外,随着峰后破坏区剪胀角的不断增加,其围岩表面位移也不同程度增加:破裂区剪胀角对其影响最为显著,软化区剪胀角次之,塑性区剪胀角影响最小。这些分析结果可为围岩稳定性分析及支护参数设计提供重要理论依据。

     

    Abstract: In order to analyze the extent of the roadway rupture zone,a four-stage stress-strain model of the surrounding rock elastic zone-plastic zone-softening zone-fracture zone of the deep roadway was established based on UST criteria and non-associated flow law,considering the influence of intermediate principal stress and the expansion coefficient. Then the closed analytical solution of stress,displacement and plastic zone radius has been deduced. Combined with engineering cases,the effects of different strength parameters,stress-strain models,dilatancy angles,and residual cohesion on the state changes of surrounding rock were analyzed. The results show that strength parameters have a significant influence on surrounding rock stress,strain,and range of post failure. With the continuous increase of strength parameters of surrounding rock,the peak stress and post-peak failure range of circumferential stress increase to varying degrees,and the stress curve shifts to the left,and the expansion coefficient is positively correlated with the strength parameters and the dilatation angle. With the increase of residual cohesive force of surrounding rock,the range of post failure and surface displacement show the non-linear decrease characteristics with a decrease of rate reducing. Compared with other stress-strain curve models,the displacement in post failure zone shows a variation characteristic with EBM>EPBM>ESM> the suggested model in this paper>EPM. Moreover,with the continuous increase of rock dialtancy in post-peak failure zone,the displacement in surface surrounding rock also increases to varying degrees. The dilation angle in the fracture zone has the most significant influence on it,followed by the dilation angle in the softening zone,and the dilation angle in the plastic zone. The analysis results can provide an important theoretical basis for the stability analysis of surrounding rock and the design of support parameters.

     

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