内钢圈加固盾构隧道黏结界面力学性能

Mechanical Properties of Bonding Interfaces of Shield Tunnels Reinforced with Inner Steel Rings

摘要:

开展静力加载条件下加固体与混凝土界面单轴拉伸与单轴剪切的单元体试验，分析了黏结界面的破坏形态、极限承载力、平均黏结强度、荷载?位移曲线以及界面应变变化规律，研究了不同黏结剂厚度、膨胀螺栓等级以及混凝土表面粗糙度对于黏结界面力学性能的影响。试验结果表明，界面拉伸条件下，黏结界面的最终破坏形态主要为混凝土内聚破坏；剪切条件下，黏结界面的最终破坏形态主要为加固体与黏结剂界面的脱开。黏结界面极限承载力和黏结强度均随黏结剂厚度的减小而增大，而界面厚度为1 mm对应的拉伸极限承载力和剪切极限承载力较2 mm厚度仅提高了4.6%和5.6%，却极大地增加了环氧树脂的注浆难度，因此选择界面厚度为2 mm更为合理。增加膨胀螺栓加固可显著提升黏结界面的拉伸和剪切强度，推荐使用M18膨胀螺栓，特殊工况下也可使用M20提升加固效果。混凝土表面越粗糙，黏结界面黏结强度就越大，其中混凝土表面粗糙度对黏结界面拉伸黏结强度的影响要大于对剪切黏结强度的影响。

Abstract:

This paper presents unit tests under static loading conditions to investigate the uniaxial tensile and shear behavior at the interface between the reinforcing material and concrete and analyzes the failure modes， ultimate bearing capacity， average bond strength， load-displacement curves， and the strain variation at the interface. Additionally， it examines the influence of different adhesive thicknesses， expansion bolt grades， and concrete surface roughness on the mechanical properties of the bond interface. The experimental results indicate that the final failure mode of the bonding interface is mainly concrete cohesive failure under interfacial tension conditions， the final failure mode of the bonding interface is mainly the detachment of the interface between the steel ring and the bonding agent under shear conditions. The ultimate bearing capacity and bonding strength of the bonding interface increase with the decrease of the adhesive thickness， while the tensile and shear ultimate bearing capacity corresponding to an interface thickness of 1mm only increase by 4.6% and 5.6% compared to a 2 mm thickness， which greatly increases the difficulty of epoxy resin grouting. Therefore， choosing an interface thickness of 2 mm is more reasonable. Adding expansion bolts for reinforcement can significantly improve the tensile and shear strength of the bonding interface. It is recommended to use M18 expansion bolts， and under special working conditions， M20 can also be used to enhance the reinforcement performance. The bonding strength of the bonding interface increases with the roughness of the concrete surface. The influence of concrete surface roughness on the tensile bonding strength of the bonding interface is greater than that on the shear bonding strength.