时变因素影响下混凝土中氯离子扩散计算方法

Calculation Method of Chlorion Diffusion in Concrete Considering Time-varying Factors

为解决现有氯离子扩散解析模型中扩散系数不能考虑温度、相对湿度等因素随时间变化的问题,通过理论推导建立了适用于任意氯离子扩散系数时变形式的解析模型。通过与现有特定时变形式下的解析模型对比,验证了所提解析模型的正确性。为便于进一步考虑因混凝土结构应力的不均匀分布、非贯通裂缝等因素导致氯离子扩散系数随空间变化的情况,提出采用等效氯离子扩散系数代替时变氯离子扩散系数的简化计算方法。该方法避免了当扩散系数随时间变化较快时,传统有限差分法计算精度与计算效率无法共存的缺点。通过与传统有限差分法的计算结果进行对比,验证了所提简化计算方法的优越性。

In the existing analytical models of chlorion diffusion in concrete,the chlorion diffusion coefficient did not take into account the influence of time-varying factors,such as temperature and relative humidity.To solve this problem,an analytical model which can consider any time-varying forms of chlorion diffusion coefficient was established by theoretical derivation.The correctness of the proposed analytical model was verified by comparing it with an existing analytical model which adopts a specific time-varying form.To further consider the spatial variation of the chlorion diffusion coefficient,which is due to the non-uniform distribution of stresses and non-through cracks in concrete structures,a simplified calculation method was proposed by replacing the time-varying chlorion diffusion coefficient with an equivalent coefficient.In the case where the diffusion coefficient changes rapidly with time,this method can avoid the disadvantage that the traditional finite difference method cannot guarantee calculation accuracy and efficiency at the same time.By comparing the calculation results with those using the traditional finite difference method,the superiority of the proposed simplified calculation method was verified.