考虑对流条件下氯离子在混凝土中的输运计算

将氯离子在混凝土中的输运区分为对流-扩散耦合区和扩散区,分别采用分离变量法和变量代换法对耦合区和扩散区氯离子输运进行求解,得到对流作用条件下氯离子在混凝土中输运的解析解.通过对耦合区解答稳定性分析确定了耦合区氯离子计算参数取值范围:叠加项n≥100,耦合区氯离子影响深度l≥1 000mm.算例分析表明,在对流作用条件下,对流深度、渗流速率和C0(初始自由氯离子质量与混凝土质量比)与C(混凝土中自由氯离子质量与混凝土质量比)累积呈正相关,但随计算时间增大,对流深度和渗流速率增大时,C差异增大,而C0增大时,C差异变小.通过对38年的对流区混凝土中C的拟合验证了计算模型的准确性.

Calculation of Chloride Ions Transportation in Concrete Considering Convection

By dividing the transportation area of chloride ions in concrete into convection diffusion coupling and diffusion areas. Separation of variables method and variable substitution method have been used to resolve chloride ions transportation equations of coupling and diffusion areas, respectively. Analytical solutions of the chloride ions transportation in concrete have been presented considering convection. Based on the stability analysis of coupling area solution, the scopes of calculation parameters are determined: superposition times n and chloride ions influence depth l must be no less than 100 and 1 000 mm, respectively. A positive correlation between convection depth, seepage velocity and initial chloride content with the accumulation of chloride ions in concrete was found by calculations and analyses. With the increase of time, the chloride ion concentration differences increase with the increase in convection depth and seepage velocity, while decrease with the increase in initial chloride content. Accuracy of the calculation model is verified by fitting the chloride ions concentration in a 38 years concrete suffering from convection.