基于细观尺度的混凝土耐久性数值分析

Numerical Analysis of Concrete Durability Based on Mesoscale

为了从细观尺度对混凝土结构耐久性问题进行数值模拟研究,阐述了混凝土内物质传输机理,建立不同传输过程的数值方程。通过对数值方程的求解,得到混凝土内物质传输过程的扩散系数及有害物质浓度,与相关试验结果对比分析表明,理论求解与试验结果吻合度较高。采用Galerkin有限元法、中心显式差分格式、迎风差分格式、Crank-Nicolson格式对数值方程进行求解,得到数值解的稳定性不同。采用Pe数判别法,且保证Pe数小于1,验证数值方程解的稳定性,其中,Crank-Nicolson格式求解的稳定性最好,表现为无条件稳定,其余3种方法求解的稳定性相同。

In order to numerically simulate the durability of concrete structures in mesoscale,the mechanism of material transport in concrete is expounded,and the numerical equations of different transport processes are established.Through solution of the numerical equations,the diffusion coefficient and the concentration of harmful substances in the concrete transport process are obtained.The comparison with the experimental results shows that the theoretical solution is in good agreement with the experimental results.The numerical equations are solved by Galerkin finite element method,central explicit difference format,upwind difference format and Crank-Nicolson format,and the stability of numerical solutions is different.The discriminant method of Pe number is used,and the Pe number is less than 1.The stability of the solution of the numerical equation is verified.The stability of the Crank-Nicolson scheme is the best,and it is unconditionally stable.The stability of other three methods is identical.