混凝土圆柱中氯离子扩散的数值分析

Numerical simulation of chloride diffusion in concrete cylinders

为了更好地理解氯离子在混凝土中的扩散机制,运用有限差分法,对混凝土圆柱在氯盐环境下服役时的氯离子扩散过程进行数值模拟,模型同时考虑了混凝土圆柱表面氯离子浓度和柱内氯离子扩散系数的时间依赖效应,得到了氯离子在混凝土圆柱截面内随时间变化的浓度分布云图。结果表明:为延长服役寿命,工程实践中可以考虑适时更换钢筋外侧的混凝土保护层,混凝土保护层的更换会产生结构内氯离子浓度的重新分布,可通过减小钢筋附近的氯离子浓度来有效延长结构服役寿命,数值模拟的结果对混凝土结构中钢筋的布筋位置具有指导意义。

To better understand the diffusion mechanism of chloride anions in concrete, a finite difference method was proposed to simulate chloride diffusion process in concrete cylinders serviced in chloride environment. Both time-dependent surface chloride concentration and chloride diffusion coefficient were taken into consideration in the model. Time-dependent concentration profiles of chloride ions in the cross-section of concrete cylinders were obtained. These numerical results provide helpful guidelines in the arrangement of steel reinforcements. To extend the service life of concrete structures, it is suggested to utilize concrete cylinders whose cover can be replaced in engineering practice. The replacement of concrete cover results in the redistribution of chloride concentration and is capable of effectively extending the service life of concrete structures.