摘要
目前针对高速列车荷载作用下隧道衬砌损伤机制的理论研究一般基于常规混凝土拉压力学特性,较少考虑外加纤维混凝土的韧性特征和破坏特性,同时也未见将纤维混凝土力学特性应用于高速铁路工程实践的例子。本文在首先开展的不同纤维种类、长度和体积掺量下的混凝土拉压力学试验基础上,基于等应变假设和Najar的损伤理论确定不同纤维种类、长度和体积掺量下混凝土的损伤参数,并在试验后通过DIC技术观察不同纤维混凝土的破坏规律,最后通过有限元数值模拟方法建立围岩-隧道结构,分析列车车速、纤维种类、长度和体积掺量等参数对隧道衬砌结构损伤发展的影响规律。结果表明:混凝土中添加纤维可以有效提高混凝土的抗损能力,同时改善常规混凝土在列车激振荷载作用下"多阶跃"损伤的发展趋势,降低隧道衬砌在列车荷载结束后的损伤终值。同等车速下,当纤维体积率低于0.15%且纤维长度较短时,3种纤维中,玻璃纤维对混凝土的抗损能力提升最多为69.5%~74.9%,PVA纤维抗损伤能力较弱为42.6%~48.8%,混合纤维能力居于两者之间。但随着纤维长度的增长和体积掺量的增大,当纤维体积率高于0.15%时,纤维在混凝土中产生的"打团"负面效应高于其"桥接"作用所带来的正效应,导致纤维混凝土峰值强度大幅降低,PVA纤维的最大抗损降幅差值可达94.3%,纤维混凝土的抗损伤能力反而低于常规混凝土,相比之下6 mm纤维在车载下稳定性和抗损提升能力方面均强于12 mm纤维。且衬砌损伤对车速大小较为敏感,车速越大损伤终值越高竖向位移峰值越大。
The existing theoretical researches on the damage mechanisms of tunnel lining under high-speed train loads,which are generally based on the tensile and compressive characteristics of conventional concrete,seldom consider the tenacity and failure characteristics of fiber concrete,and very limited practice examples of fiber concrete applied to high speed railway are documented in literature.In this paper,a series of fiber concrete experiments with different fiber types,lengths,and volume ratios were conducted to obtain the tensile and compressive characteristics of fiber concrete,and the failure characteristics of different fiber concretes were observed by the DIC technology after the experiments.The concrete damage parameters were determined based upon the equal strain assumption and Najar’s damage theory,and the effects of the type,length and volume ratio of fiber on the damage development of the tunnel lining under the excitation force caused by trains at different speeds were analyzed by utilizing the finite element method to simulate the rock mass and the tunnel structure.The results indicate that the fiber can effectively improve the damage resistance of concrete.Specifically,the fiber in concrete can alleviate the multi-step damage development under train excitation loads and greatly reduce the final damage of tunnel lining after train loading.When the volume ratio of the fiber with a shorter length is lower than 0.15%,the glass fiber achieves the greatest improvement in the damage resistance of concrete by 69.5%to 74.9%,followed by mixed fiber,and the improvement by the PVA fiber is only 42.6%to 48.8%.However,when the volume ratio is higher than 0.15%,the negative effect resulted from fiber clustering overweighs the positive effect caused by its bridging,resulting in a significant reduction in the peak strength of fiber concrete.The maximum reduction value of the PVA fiber is 94.3%,which makes the damage resistance of the fiber concrete inferior to that of the conventional concrete.In addition,it is observed that the performance enhancement in damage resistance of 6 mm fiber is higher than that of 12 mm fiber.The train speed has a great influence on the final damage value of fiber concrete lining,and both the final damage value and the vertical peak displacement increase with increasing the train speed.
作者
张治国
冯驹
张孟喜
王志伟
马伟斌
ZHANG Zhiguo;FENG Ju;ZHANG Mengxi;WANG Zhiwei;MA Weibin(School of Environment and Architecture,University of Shanghai for Science and Technology,Shanghai 200093,China;State Key Laboratory for Track Technology of High-speed Railway,China Academy of Railway Science,Beijing 100081,China;Department of Civil Engineering,Shanghai University,Shanghai 200444,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2020年第12期2483-2504,共22页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(41977247,41772331)
高速铁路轨道技术重点实验室基金项目(2018YJ181)。
关键词
隧道工程
衬砌
损伤机制
混凝土试验
纤维混凝土
列车激振荷载
tunnel engineering
lining
damage mechanism
concrete experiments
fiber concrete
train excitation load
作者简介
张治国(1978-),男,2001年毕业于武汉理工大学交通土建工程专业,现任副教授,主要从事地下工程施工对周边环境影响控制等方面的研究工作。E-mail:zgzhang@usst.edu.cn。
