摘要
采用现场测试方法,对隧道底部结构的变形、仰拱混凝土和钢筋中的应力进行了长期测试和分析。受围岩释放荷载、隧道二衬自重及上部围岩荷载以及道床设施和运营列车荷载的作用,隧道底部结构在整个施工过程中经历了隆起—下沉—隆起—下沉的反复变化过程,仰拱混凝土及钢筋同样经历了拉—压—拉—压的反复变化过程;围岩条件越好,隧道底部结构中的应力和变形最终值及其变化幅值越小;整个隧道施工过程中,隧道底部结构的最大下沉小于5.0 mm,混凝土中的最大拉压应力小于2.0 MPa,满足高速列车的安全运营要求;隧道二次衬砌施作之前仰拱处于最不利的受力状态,施工中应及时将隧道二衬闭合成环,以保证隧道仰拱结构处于较佳的受力状态;隧道开挖后的应力重分布持续时间一般在2 a以上。
By means of the in-situ monitoring method,the deformation of bottom structure of tunnel and the stress of concrete and rebars in its inverted arch are tested and analyzed.Under the action of unloading of surrounding rock,the loads of tunnel linings,and the upper surrounding rock auxiliary facilities and train load,the bottom structure of the tunnel witnesses a repeated process of uplift-subsidence-uplift-subsidence during the whole course of tunnel construction,and the concrete and rebars in the inverted arch have a process of tension-compression-tension-compression as well.The better the condition of the surrounding rock,the smaller the values of the deformation and stress and their change ranges.During the whole course of tunnel construction,the maximum subsidence of the bottom structure of the tunnel is less than 5.0 mm,and the maximum tensile and compression stresses are both less than 2.0 MPa,thus high-speed trains can run safely.The inverted arch of the tunnel is in the worst conditions before the tunnel linings are constructed.So the tunnel linings must be constructed in time to make sure that the inverted arch is under better conditions.The redistribution time of the stress on the surrounding rock after tunnel excavation is generally more than two years.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2012年第5期879-884,共6页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(50808176)
铁道部重大计划项目(2005K002-A-1)
关键词
隧道
底部结构
应力
变形
长期测试
tunnel
bottom structure
stress
deformation
long-term monitoring
