地震作用下大断面隧道衬砌结构的动力损伤特性

基于混凝土材料的动力损伤特性，建立了其弹塑性损伤本构模型，将该模型应用于强震区某大断面隧道工程，分析了不同地震波入射方向、地震波强度和围岩条件下隧道结构的地震响应与动力损伤规律，探讨了大断面隧道结构的地震损伤特性和破坏机理。研究结果表明：地震波垂直、水平两种入射条件下两者衬砌的压主应力、加速度响应形态相似，但水平入射条件下衬砌结构的应力、加速度响应相较于垂直入射条件更加剧烈；水平入射时衬砌的动力损伤远大于垂直入射时的动力损伤，且动力损伤主要集中于拱腰与墙脚处；围岩条件对隧道衬砌结构的拉主应力响应以及动力损伤有显著影响，V级围岩条件下衬砌结构的最大拉应力是IV级围岩下的5.7倍；隧道结构的地震响应与动力损伤特性也受地震波强度的影响，随着地震波强度增大，应力、加速度响应峰值以及最大动力损伤量均呈现非线性增大趋势，动力损伤随之加剧且由拱腰和墙脚处逐渐向外扩展；在强震区软岩隧道抗震设计以及运营期间震后加固修复应着重注意动力损伤集中的部位。

Dynamic Damage Characteristics of Large Section Tunnel Lining Under Seismic Load

Based on the dynamic damage characteristics of concrete material, this paper established an elastoplastic damage constitutive model, which was applied to a tunnel project with large section in a strong earthquake area. It analyzed the seismic response and dynamic damage law of tunnel structure under different incident directions of seismic waves, seismic wave intensity and surrounding rock conditions, and discussed the seismic damage characteristics and failure mechanism of large section tunnel structure. The results show that the principal stress and acceleration responses of the lining are similar under vertical and horizontal incidence conditions, but the stress and acceleration responses of the lining structure under horizontal incidence conditions are more intense than that under vertical incidence conditions. The dynamic damage of the lining at horizontal incidence is much greater than that at vertical incidence, and the dynamic damage is mainly concentrated at the arch waist and the foot of the wall. The surrounding rock conditions have significant influence on the tensile principal stress response and dynamic damage of the tunnel lining structure. The maximum tensile stress of the lining structure under V-level surrounding rock is 5.7 times of that under IV level surrounding rock. The seismic response and dynamic damage characteristics of tunnel structure are also affected by the intensity of seismic waves. With the increase of seismic wave intensity, the peak value of stress, acceleration response and the maximum amount of dynamic damage show a nonlinear increase trend, and the dynamic damage intensifies and gradually expands outward from the waist and the foot of the wall. In the seismic design of soft rock tunnel in strong earthquake area and the post-earthquake reinforcement and repair during operation, attention should be paid to the parts where the dynamic damage is concentrated.