钢纤维混凝土管片结构力学特性研究  

Mechanical properties of steel fiber reinforced concrete segment lining

作　　者：张帆[1] 张戈 徐秀峰 柳献[1] ZHANG Fan;ZHANG Ge;XU Xiufeng;LIU Xian(Department of Geotechnical Engineering,College of Civil Engineering,Tongji University,Shanghai 200092,China;Hangzhou Branch of Beijing Urban Construction Design and Development Group Co.,Ltd.,Hangzhou 310017,China)

机构地区：[1]同济大学土木工程学院地下建筑与工程系,上海200092 [2]北京城建设计发展集团股份有限公司杭州分公司,浙江杭州310017

出　　处：《铁道科学与工程学报》2023年第9期3463-3475,共13页Journal of Railway Science and Engineering

基　　金：浙江省建设科研项目(2021K189);杭州市建设科研项目(2021028)。

摘　　要：为探究钢纤维混凝土管片结构力学性能,对主筋用量不削减、掺入30 kg/m3钢纤维的钢筋钢纤维混凝土管片结构开展极限承载力试验。管片错缝拼装形成试验结构,通过环向24组千斤顶模拟水土作用对结构施加荷载,通过逐步减小腰部荷载模拟侧部卸载工况,直至结构破坏。在卸载工况下,结构每环在0°,90°,180°或270°等弯矩较大位置附近的3处纵缝先后发生混凝土压裂和压碎,最终在0°或180°附近管片钢筋屈服、混凝土压碎,结构形成4个塑性铰破坏。根据试验测试的应变数据对结构内力进行计算,分析钢纤维混凝土对结构刚度和承载力的提升作用。研究结果表明,相比普通混凝土结构,在刚度方面,管片初裂时,钢纤维混凝土管片刚度提升6.91%,当裂缝宽度超过0.2 mm时,钢纤维混凝土管片刚度提升3.45%,提升作用降低的原因是随着荷载增大,钢筋应力逐渐增加,钢筋对管片刚度的作用增大而钢纤维混凝土对刚度作用基本不变;接头混凝土压裂时,钢纤维混凝土接头刚度提升18.7%。在承载方面,钢纤维混凝土管片极限承载力提升6%,接头极限承载力提升3%,整体结构极限承载力提升4.2%。并且,由于钢纤维混凝土对接头刚度的提升作用以及对环缝抗剪性能的提升作用,钢纤维混凝土结构环缝破坏发生于纵缝压碎之后,破坏过程与普通混凝土结构存在明显差别。Full scale test was carried out on steel fiber reinforced concrete(SFRC)segment lining to study its mechanical properties.The fiber content was 30 kg/m3,and no rebar was substituted by fiber.The staggered joint lining was loaded by 24 sets of jacks.The inner force of lining caused by ground was simulated by these jacks.Then the loads at the waist of lining was unloaded until the structure was destroyed.In those tests,the concrete of three longitudinal joints in each ring nearby 0°,90°,180°or 270°where the moments were bigger was cracked and crushed.Then combine with rebar yielded and concrete crashed at 0°or 180°,four plastic hinges were generated in each ring,inducing completely destruction.The inner force was calculated through strain obtained in the test,and the strengthening effect on stiffness and bearing capacity resulted by SFRC was analyzed.For stiffness,the stiffness of SFRC segment is increased by 6.91%when initial crack appears,compared with reinforced concrete(RC)segment without fiber.But the increasement is 3.45%when the crack width exceeds 0.2 mm.The reason why the strengthening effect decreases is that,with the increase of loads,stress in steel bar is increased,and plays a more important role in remaining stiffness,while the effect of SFRC is almost constant.The stiffness of SFRC longitudinal joint is increased by 18.7%when the initial compressive crack appears.For bearing capacity,the ultimate bearing capacity is increased by 6%for SFRC segment,and 3%for SFRC longitudinal joint,and 4.2%for SFRC lining.At the same time,the failure mode of SFRC lining is obviously different from that of RC lining,the circumferential joint failure occurs after longitudinal joint crushing due to the enhancement of longitudinal joint stiffness and circumferential joint shear performance caused by SFRC.

关 键 词：钢纤维混凝土管片 刚度 承载力 足尺试验 破坏模式 

分 类 号：U45[建筑科学—桥梁与隧道工程]