顾及沉积岩应变强化与扩容效应的围岩弹塑性力学状态理论分析

Analytical Research for Elastoplastic Mechanical Response Considering Strain-Hardening and Dilatancy of Sedimentary Rock

根据非关联流动法则与中主应力表达式,顾及沉积岩应变强化和扩容效应,推导基于幂强化-理想塑性本构模型和Drucker-Prager屈服准则的应力、位移、塑性区半径的解析解.将文中解、幂强化解、幂强化-理想塑性解进行比较,分析幂强化指数与扩容角对解析解的影响规律.结果表明:幂强化指数对围岩稳定性有较大的影响;扩容程度的变化对围岩应力和位移的影响随着扩容角及原岩应力的增加而增大;当隧洞围岩受到应变强化和扩容效应共同影响时,幂强化指数与扩容角越大,隧洞围岩位移越为敏感,对围岩稳定十分不利.

Analytical solutions of stress,displacement and plastic zone radius are obtained with power-hardening model based on Drucker-Prager failure criterion,which adopts the intermediate principal stress expression and non-associated flow rule,and the dilatancy effect is took into account.The paper compares the results of dilatant power hardening-perfectly plastic model and power-hardening model,power hardening-perfectly plastic model respectively,the influence of power-hardening index and dilatancy angle on analytical solutions of surrounding rock are discussed.The results show that the effect of power-hardening index is of great impact on the stability of surrounding rock,the influence of dilatancy extent on the surrounding rock stress and displacement increases as the dilation angle and in-situ stress increase.The tunnel surrounding rock is affected by both the strain-hardening effect and the dilatancy effect,when the power-hardening index and dilatancy angle increase,the displacement is more sensitive,which is unfavorable to the tunnel stability.