侧向荷载作用下公路隧道衬砌损伤演化分析

为了研究侧向荷载作用下隧道衬砌的损伤演化机制,采用1∶10相似模型试验分析了隧道结构在侧向荷载下的受力变形特征、破坏形式和损伤过程,基于试验结果利用数值计算反演分析了衬砌结构刚度衰减规律。研究表明:侧向荷载下隧道受力变形过程分为4个阶段:弹性受力阶段、拱腰开裂阶段、保护层局部破碎剥离阶段、结构软化破坏阶段;结构破坏模式表现为拱肩位置的斜剪破坏,关键部位破坏顺序为“拱腰开裂—拱肩脆性剪坏—拱腰延性破坏”,破坏时形成三铰拱可变体系。衬砌结构刚度在拱腰开裂后快速衰减,结构丧失承载力时刚度衰减幅度为84%;考虑隧道安全性评价,以结构技术状况评定值为界,结构在无破损、轻微破损、中等破损、严重破损、危险状态下的刚度折减系数分别为0.95、0.57、0.33、0.21、0.16。

Analysis on Damage Evolution of Highway Tunnel Lining under Lateral Load

In order to study the damage evolution mechanism of tunnel lining under lateral load, the 1∶10 similar model test was used to analyze the stress and deformation characteristics, failure modes and damage process of tunnel structure under lateral load, and based on the test results, the attenuation law of lining structural stiffness was analyzed by numerical calculation. The results show that the deformation process of tunnel under lateral load is divided into four stages: elastic stress stage, arch waist cracking stage, protective layer partial crushing and stripping stage, structural softening failure stage. The failure mode of the structure is inclined shear failure at the position of the arch shoulder, and the failure sequence of the key parts is arch waist cracking, arch shoulder brittle shear failure, arch waist ductile failure, and a three-hinged arch variable system is formed during failure. The stiffness of the lining structure decays rapidly after the arch waist cracks, and the attenuation range of the stiffness is 84% when the structure loses its bearing capacity. Considering the tunnel safety evaluation, taking the evaluation value of the structural technical condition as the boundary, the stiffness reduction coefficients of the structure under the condition of no damage, slight damage, medium damage, severe damage and danger are 0.95, 0.57, 0.33, 0.21 and 0.16 respectively.