摘要
围岩流变效应导致的衬砌开裂是软弱围岩地层隧道服役期间较易遭遇的问题。针对该问题,以某软弱破碎千枚岩隧道为例,在对该隧道二衬开裂情况及原因进行调查的基础上,建立锚杆-围岩复合体结构流变模型及基于壳-接头的二次衬砌开裂模型,对二次衬砌在不同裂损程度、不同开裂位置及不同裂纹数量下结构的长期安全性进行了分析。结果表明:单条裂纹情况下,随着裂纹深度的增加,隧道各开裂截面处安全系数逐渐减小,拱顶、拱肩、拱腰处几乎呈线性降低,而拱底的安全系数变化最为显著;相对于开裂截面,未开裂截面由于刚度大,对流变荷载的反应更为敏感,即截面的安全系数随着衬砌服役年限的增加变化更为剧烈,部分截面安全系数甚至会降至1以下;当η>0.7(η为裂缝截面刚度折减系数)时,结构的安全性主要受流变荷载控制,当0.5<η<0.7时,结构的安全性受流变荷载及截面裂损程度的共同控制,当η<0.5时,结构的安全性主要受截面裂损程度的控制;在实际工程中,结构出现两处裂纹时,当裂损程度η=0.5时对结构进行加固是比较适宜的;而结构出现三处裂纹时,当裂损程度η=0.7时对结构进行加固是比较适宜的。
The crack of lining caused by rheological effect of surrounding rock is a problem that is easy to encounter during service period of tunnel in weak rock stratum. To solve this problem, a weak and crushing phyllite tunnel is taken as an example. Based on the survey on crack conditions and causes of secondary lining, two models are established： rheological model of anchor-rock composite structure and crack model of secondary lining based on shell-joint. For different damage degrees, different crack positions and different quantities of cracks of secondary lining, long-term safety of structure is analyzed. The results show that, under action of a single crack, the safety factor of tunnel is gradually reduced with the increase of the crack depth. The safety factors for vault, spandrel and haunch may decrease almost linearly, while the decrease of safety factor for vault is most significant. Compared to the cracked sections, uncracked sections are more sensitive to rheological load due to the high stiffness. The safety factors of uncracked sections may decrease more remarkably with the increase of service life, and the safety factors of some sections may even be reduced to below 1. When η（ damage degree） is greater than 0. 7, the safety of structure is mainly controlled by rheological load. When η is between 0.5 and 0.7, the safety of structure is controlled by rheological load and damage degree. When η is smaller than 0.5, the safety of structure is mainly controlled by damage degree. In practical applications, when two cracks occur in secondary lining, strengthening the structure is appropriate when η is equal to 0.5. While three cracks occur in the structure, strengthening the structure is appropriate when η is equal to 0.7.
出处
《土木工程学报》
EI
CSCD
北大核心
2016年第12期114-123,共10页
China Civil Engineering Journal
基金
863计划子课题(2014AA110401)
煤炭联合基金重点项目(U1361210)
国家自然科学基金(515784560)
中央高校基本科研业务费专项资金资助(2682015CX092)
关键词
流变
二次衬砌
隧道开裂
壳
接头
rheological load
secondary lining
tunnel cracking
shell
joint
