摘要
为研究多尺度聚丙烯纤维混凝土在隧道二衬中的应用,开展多尺度聚丙烯纤维混凝土室内试验和现场试验,选用2种聚丙烯细纤维和1种聚丙烯粗纤维进行混掺,综合评估了多尺度聚丙烯纤维混凝土的坍落度、抗裂性、抗压强度和劈裂抗拉强度。结合重庆某山区公路隧道病害整治工程,选取地质条件相近的两个Ⅴ级围岩衬砌拆换段分别作为试验段和对比段进行了现场试验。结果表明:多尺度聚丙烯纤维混凝土抗压强度略有降低,但在满足现场泵送要求的同时,多尺度聚丙烯纤维的掺入能提高混凝土的劈裂抗拉强度,其劈裂破坏具有一定的延性;粗、细纤维的“桥接”作用能有效抑制裂缝的形成和发展,延缓混凝土起裂时间,减小裂缝的长度和宽度,粗、细聚丙烯纤维产生了1+1>2的混杂正效应,使得多尺度聚丙烯纤维在混凝土开裂全过程均起到良好的阻裂效果;浇注过程中,多尺度聚丙烯纤维混凝土未出现泌水、离析和堵管等不良现象,纤维分散性良好;衬砌结构成型180 d后,其强度满足设计要求,两段衬砌结构表面平整、光滑,均未发现肉眼可见裂缝,表明多尺度聚丙烯纤维混凝土可用于隧道二衬;由于使用时间还不够长,更多后期二衬情况有待进一步监测。
In order to study the application of multi-scale polypropylene fiber concrete in secondary lining of tunnel,and to carry out the indoor and field tests of multi-scale polypropylene fiber concrete,selecting 2 kinds of polypropylene fine fiber and 1 kind of polypropylene coarse fiber for mixing,the slump,crack resistance,compressive strength and splitting tensile strength of multi-scale polypropylene fiber concrete are comprehensively evaluated.Based on a highway tunnel disease treatment project in a mountainous area of Chongqing,selecting 2 Class V surrounding rock lining replacement sections with similar geological conditions as experimental and comparative sections,the on-site test is conducted.The result shows that(1)the compressive strength of multi-scale polypropylene fiber concrete is slightly reduced,while meeting the on-site pumping requirements,the addition of multi-scale polypropylene fiber can improve the splitting tensile strength of concrete,and its splitting failure has a certain degree of ductility;(2)the“bridging”effect of coarse and fine fibers can effectively suppress the formation and development of cracks,postpone the initiation time of concrete cracking,and reduce the length and width of cracks.Coarse and fine polypropylene fibers produce a hybrid positive effect of 1+1>2,which enables multi-scale polypropylene fiber to have a good crack resistance effect in the whole process of concrete cracking;(3)during the pouring process,the multi-scale polypropylene fiber concrete did not exhibit any adverse phenomena such as bleeding,segregation and pipe blockage,and the fiber dispersity is good;(4)after 180 days from forming the lining structure,its strength meets the design requirements,the surfaces of the 2 lining structures are flat and smooth,and no visible cracks are found,indicating that multi-scale polypropylene fiber concrete can be used for tunnel secondary lining;(5)due to the insufficient usage time,more later second lining conditions need to be further monitored.
作者
梁宁慧
周侃
毛金旺
刘新荣
任联玺
LIANG Ning-hui;ZHOU Kan;MAO Jin-wang;LIU Xin-rong;REN Lian-xi(School of Civil Engineering,Chongqing University,Chongqing 400000,China;National Joint Engineering Research Center of Geohazards Prevention in Reservoir Areas,Chongqing University,Chongqing 400000,China)
出处
《公路交通科技》
CSCD
北大核心
2023年第9期158-165,共8页
Journal of Highway and Transportation Research and Development
基金
中交资产管理有限公司科研课题项目(H20211094)
重庆市研究生科研创新项目(CYS21029)。
关键词
隧道工程
二衬
现场试验
聚丙烯纤维混凝土
多尺度
tunnel engineering
secondary lining
field test
polypropylene fiber concrete
multi-scale
