硫酸盐侵蚀后地铁盾构隧道纵缝接头抗弯力学模型

Bending Mechanical Model of Longitudinal Joint in Metro Shield Tunnel After Sulfate Attack

摘要:

基于地铁盾构隧道混凝土被硫酸盐侵蚀实际工况，建立了能够考虑接缝细部构造、表面混凝土及螺栓等且接缝截面可离散为不同类型受压区的纵缝接头正弯矩力学模型。采用全积分形式进行混凝土本构关系运算，适用分析混凝土被硫酸盐侵蚀后接缝面混凝土压碎、螺栓屈服以及接头极限状态。结合数值计算进行对比分析，两者结果基本一致，验证了力学模型合理性。研究结果表明：正弯矩作用下，混凝土被硫酸盐侵蚀对纵缝接头力学性能的影响主要表现在外表面边缘混凝土接触之后。随着硫酸盐侵蚀时间的增长，纵缝接头极限弯矩不断减少，但减幅较为平均。同时，各变形量最大值也随着侵蚀时间的增长而减小，但减幅各自不同。随着硫酸盐侵蚀厚度的增大，纵缝接头极限弯矩及各变形量最大值均不断减少，且减幅不断增大。

关键词:盾构隧道;纵缝接头;抗弯性能;力学模型;硫酸盐侵蚀

Abstract:

Based on the actual condition of concrete sulfate attack in metro shield tunnel, the sagging moment mechanical model of longitudinal joint is established, which can take into account the details of joint structure, surface concrete and bolts. Furthermore the joint section can be discretized into different compression zones. Because the constitutive calculation of concrete is carried out in full integral form, it is adapted to analyze the crush of concrete, the yield of bolt and the limit state of longitudinal joint. Comparing with numerical calculation, the results of the two methods are basically the same, which verifies the rationality of the mechanical model. The results show that under sagging moment, the effect of sulfate attack on the mechanical property of longitudinal joint is mainly manifested after the contact of concrete at the outer surface edge. Against the increasing of sulfate attack time, the ultimate bending moment of longitudinal joint decreases continuously with an average margin. Meanwhile, the maximum deformation decreases against the increasing of attack time with a different decreasing margin. When the sulfate attack thickness increases, the ultimate bending moment and the maximum deformation of longitudinal joint decrease continuously with a larger margin.

Key words:shield tunnel;longitudinal joint;bending property;mechanical model;sulfate attack