中文摘要：

基于自然电位法设计了梯形电极监测系统,然后通过钢筋锈蚀加速试验,对2种水灰比混凝土试件中沿保护层厚度方向梯形分布的各层光圆钢筋锈蚀进行了监测.结果表明：沿保护层厚度方向梯形分布的各层光圆钢筋依次发生锈蚀,各层光圆钢筋开始锈蚀时间间隔渐次增加;光圆钢筋开始锈蚀时间与保护层厚度之间关系可采用指数函数方程拟合,拟合结果与试验数据吻合良好;2种水灰比混凝土中各层光圆钢筋开始锈蚀时的临界氯离子含量（质量分数）为0.3%~0.5%.梯形电极监测系统可有效追踪混凝土中的钢筋锈蚀行为,对混凝土结构安全性提供及时预警.

英文摘要：

Ladder-shaped-electrode monitoring system was designed based on the self-potential method to study the corrosion processes of plain steel bars which were embedded at different depths in concrete. Re- sults indicate that the embedded plain steel bars corrode in turn with the increasing of cover thickness. The interval between the initial corrosion times of two adjacent plain steel bars grows gradually. The relation- ship between the initial corrosion time and cover thickness can be fitted by exponential equation. The fitted results coincide with experimental data well. The critical chloride ion contents for plain steel bar corrosion are 0.3%-0. 5% （by mass） in two types of concrete. The ladder-shaped-electrode monitoring system can trace the corrosion process of steel bar in concrete. In this way it provides early warning in time against po- tential safety loss of concrete structures.