摘要
衬砌作为隧道工程结构的重要组成部分,其施工质量是影响隧道结构安全性和耐久性的主要因素之一,隧道二次衬砌混凝土具有体积大、强度高、边界约束大等特点,易导致二次衬砌混凝土开裂。本文以某铁路隧道二次衬砌混凝土开裂案例为依托,初步分析该工程二次衬砌混凝土开裂的原因,其次结合MIDAS/Fea 3.7有限元分析软件,建立二次衬砌环在有约束和无约束两种状态下的仿真模型,并分别对衬砌结构的纵向温度应力、环向温度应力进行对比分析,探明影响二次衬砌混凝土裂缝的成因。结果表明,二次衬砌裂缝属于混凝土早期温度应力裂缝,是二次衬砌混凝土降温收缩变形受到外侧喷射混凝土衬砌约束的情况下产生的。其次,衬砌受到的约束越大,温度应力值越大,二次衬砌结构混凝土更容易开裂,而复合式衬砌中的柔性夹层可以有效降低约束,以减小现浇二次衬砌混凝土开裂风险。
As an important part of tunnel engineering structure,the lining construction quality is one of the main factors affecting the safety and durability of tunnel structure.The concrete of tunnel secondary lining has the characteristics of large volume,high strength and large boundary constraint,which easily leads to the cracking of the concrete of tunnel secondary lining.Based on the cracking case of the secondary lining concrete of a railway tunnel,this paper preliminarily analyzed the causes of the cracking of the secondary lining concrete of the project.Then,combined with the FINITE element analysis software MIDASZFea 3.7,the simulation model of the secondary lining ring with and without constraints was established.The longitudinal temperature stress and circumferential temperature stress of the lining structure were compared and analyzed respectively to find out the causes and main risk locations of cracks affecting the secondary lining concrete.The results show that the cracks in the secondary lining belong to the temperature stress cracks in the early stage of concrete,and are caused by the cooling and shrinkage deformation of the secondary lining restricted by the outer shotcrete lining.Secondly,the more constrained the lining is,the greater the temperature stress value is,and the concrete of the secondary lining is more likely to crack.The flexible interlayer in the composite lining can effectively reduce the constraint to reduce the cracking risk of the cast-in-place secondary lining concrete.
作者
段乐婷
DUAN Leting(School of Civil Engineering,Xi'an Traffic Engineering Institute,Xi'an 710300,China)
出处
《西安交通工程学院学术研究》
2022年第1期14-17,22,共5页
Academic Research of Xi'an Traffic Engineering Institute
关键词
隧道二次衬砌
混凝土裂缝
数值模拟
tunnel secondary lining
concrete crack
numerical simulation
