钢筋锈蚀对上海地铁盾构隧道纵缝接头抗弯力学性能影响研究

Influence of Reinforcement Corrosion on Bending Mechanical Property of Longitudinal Joint in Shanghai Metro Shield Tunnel

为研究钢筋锈蚀后上海地铁盾构隧道纵缝接头抗弯力学性能退化规律,基于地铁盾构隧道环境条件及空间分布,对管片进行氯盐侵蚀加速钢筋锈蚀试验,并以此为基础进行纵缝接头正弯矩足尺试验。建立纵缝接头三维数值精细化计算模型,并分析钢筋锈蚀影响下地铁盾构隧道纵缝接头的力学性能退化状况。对足尺试验和数值计算结果进行对比分析,结果表明:1)在正弯矩作用下,钢筋锈蚀后纵缝接头的变形规律具有明显的阶段性特征。足尺试验中,纵缝接头变形可以划分为3个阶段。数值计算中,可定义6个特征点,纵缝接头变形划分为7个阶段。2)纵缝接头变形前6个阶段,钢筋锈蚀对主要变形特征值无明显影响。至最后一个阶段,随着钢筋锈蚀层厚度的增加,螺栓应变及极限承载力均减小。螺栓应变最大值减幅较大,极限承载力减幅较小。3)钢筋锈蚀后纵缝接头在正弯矩作用下,主要破坏形式为螺栓拉弯、端肋被拉断、外表面边缘混凝土剥离及压碎。

In order to study the degradation of bending mechanical property of longitudinal joint in Shanghai Metro shield tunnel induced by reinforcement corrosion,accelerated reinforcement corrosion experiments of segment in the environment of chloride attack and full-scale tests with sagging moment are conducted based on the environmental condition and spatial distribution of metro shield tunnel.A 3D refined FEM model of longitudinal joint is established to analyze the deterioration status of longitudinal joint mechanical property under the influence of reinforcement corrosion.The results of full-scale test and numerical simulation are compared and analyzed,and the comparison results show that:(1)Under the effect of sagging moment,the deformation of longitudinal joint after reinforcement corrosion has obvious periodical characteristics;in the full-scale test,the deformation of longitudinal joint can be divided into 3 stages;and in the numerical simulation,the deformation of longitudinal joint can be divided into 7 states considering the definition of 6 feature points.(2)In the first 6 stages,the reinforcement corrosion affects the deformation of longitudinal joint little;while in the last stage,as the thickness of reinforcement corrosion increases,the bolt strain and ultimate bearing capacity reduce;the maximum bolt strain decreases greatly and ultimate bearing capacity decreases small.(3)Under the effect of sagging moment,the major failure modes of longitudinal joint after reinforcement corrosion include bolt stretch bending,end ribbed reinforcement snapped and edge concrete of outer surface stripping and crushed.