砂浆内钢筋锈胀应力监测与数值模拟研究

钢筋锈蚀是导致海洋混凝土结构失效破坏的最主要原因，探明钢筋锈胀应力发展及其诱导混凝土开裂的过程对于钢筋混凝土服役寿命预测有重要意义。采用内掺盐与恒电位加速砂浆内钢筋锈蚀，通过砂浆外不锈钢圆环环贴应变片实现钢筋锈蚀过程的应变监测，并计算锈胀应力，利用COMSOL软件分析混凝土中钢筋锈胀应力发展及混凝土锈胀开裂历程。结果表明：利用有限元与钢筋锈胀时变径向位移加载，实现钢筋混凝土锈胀开裂过程的模拟，模拟结果与试验结果基本一致；不考虑砂浆、钢筋的非均匀性及锈蚀产物对开裂砂浆的充填效应，模拟结果不能真实反映锈胀应力的波动性及锈胀应力释放与缓慢增加的过程；提高砂浆强度、减小钢筋直径可以有效延缓钢筋锈胀导致混凝土开裂的时间。

Experimental and numerical simulation study on corrosion evolution of steel bar in mortar

Reinforcement corrosion is the primary cause of the failure of marine concrete structures. Thus, it is necessary to explore the development of corrosion expansion stress and the process of induced concrete cracking, which is beneficial to the service life prediction of reinforced concrete. In the experiments, the reinforcement corrosion in mortar is accelerated by adding salt and using constant potential. The strain in the reinforcement corrosion process is monitored by the strain gauge attached to the stainless steel ring outside the mortar to calculate the corrosion expansion stress. The COMSOL software is used to analyze the development of corrosion expansion stress in concrete and the whole concrete cracking process induced by reinforcement corrosion. The results show that the finite element method and the time-varying radial displacement loading method can be used in simulating and testing the corrosion expansion and cracking process of reinforced concrete respectively, the results of which are basically consistent. Without considering the inhomogeneity of mortar and reinforcement and the filling effect of corrosion products on cracked mortar, the simulation results fail to reflect the fluctuation and the process of release and gradual increase of corrosion expansion stress. In addition, by increasing the mortar strength and decreasing the reinforcement diameter, corrosion expansion and cracking of reinforcement can be effectively delayed.