基于蠕变终止轨迹的巷道围岩粘弹塑性分析

Elastic-viscoplastic analysis of roadway surrounding rock based on creep terminated trajectory

引入稳定巷道围岩中的峰值应力为一定围压下围岩的长期强度的观点,将巷道围岩分为弹、塑性区;考虑围岩流变、塑性扩容及中间主应力的影响,基于Drucker-Prager准则对圆形巷道围岩的弹塑性进行了分析,推导出相应的应力、位移及塑性区半径的解析解;考虑岩体特征值(E,μ)与时间和应力有关,基于西原模型采用Laplace变换法对所得结果进行了修正,得到围岩粘弹性位移解;在相关文献试验基础上,进行了实例计算并与ABAQUS模拟结果对比。结果表明:围岩流变特性对巷道变形及塑性区的扩展具有重要影响,以一定围压下围岩的长期强度为巷道围岩应力峰值,能够在一定程度上反映围岩流变特性对巷道围岩变形的影响,符合工程实际;粘弹性位移与数值模拟解吻合较好。本研究对巷道长期稳定性理论及地下巷道支护具有一定的参考意义。

Based on creep terminated trajectory theory,the paper demonstrates the peak stress in stabilized roadway surrounding rock is the long-term strength of surrounding rock mass with a certain confining pressure and derives analytic solutions of stress,displacement and radius of plastic area based on Drucker-Prager criterion by considering the influence of surrounding rock rheology,plastic expansion and intermediate principal stress;The obtained solution of roadway is modified based on Xiyuan model and Laplace transform method by considering the rock mass eigenvalues(E,μ)are related to time and stress,and the viscoelastic displacement solution of surrounding rock is obtained.Later in this article,it carries out a case study and contrasts it with ABAQUS numerical result.Study results show surrounding rock's rheology has great impact on roadway surrounding rock deforming and plastic zone expanding.It can can reflect the impact of rheology on deformation of roadway surrounding rock to a certain extent to regard the long-term strength of surrounding rock mass with a certain confining pressure as the peak stress of in stabilized roadway surrounding rock.Furthermore,the viscoelastic roadway displacement fits preferably with the numerical simulation.The study can provide theoretical basis for surrounding rock long-term stability evaluation and supporting quantitative design.