隧洞围岩损伤演化与时效破坏过程的模拟分析

Numerical Analysis on Damage Evolution and Time-dependent Failure of Rock Surrounding Underground Tunnel

依据对岩石长期强度的认识,基于环境因素影响下岩石强度、弹模等物理力学性质随时间劣化及其内部细观损伤积累等观点,应用RFPA数值模拟方法,模拟了隧洞围岩的时效破坏过程,并与相应的物理模型试验结果进行了对比。隧洞数值模拟试验得到了拱顶、拱底以及两侧帮的时效变形特征曲线,与实际物模试验结果表现出了较好的一致性,并且发现隧洞围岩宏观破坏是细观损伤实时演化及逐步积累的最终表现。进一步模拟分析了侧压系数对隧洞时效变形破坏特性的影响,模拟结果显示,随着侧压系数的增大,隧洞左右边墙间的闭合位移逐渐增大,而隧洞拱顶拱底间的收敛位移随侧压系数的增大逐渐减小,并对隧洞围岩的局部的细观损伤演化过程及宏观时效破坏模式做出了清晰的解释。

Based on the knowledge of long-term strength of rocks, time-dependent failure process of rock surrounding underground tunnel are simulated, by applying RFPA, in view of characteristics of rocks that physical and mechanical properties, strength and elasticity modulus etc., are degraded and macroscopic damage accumulation with time due to the influence of environmental variation. Compared with the results of physical model test, time- dependent deformation curves of roof, floor and walls from numerical simulation of tunnel were generally consistent with those from physical model test, and it was concluded that macroscopic failure of rock surrounding underground tunnel was a macroscopic damage consequence of time-dependent evolution and progressive accumulation. As a parameter analysis ease, the impact of lateral pressure coefficient on time-dependent deformation and failure characteristics of tunnel was also simulated. The results show the wall-to-wall closure displacement of tunnel increases gradually with increase of lateral pressure coefficient, while roof-to-floor convergence displacement decreases gradually. Local macroscopic damage evolution and macroseopical time-dependent failure of tunnel surrounding rock also are explained.