论文部分内容阅读
以北京市阳坊地区地表新鲜花岗岩为实验介质 ,在含有天然裂隙面切割的花岗岩柱中进行了核素扩散实验。考虑了花岗岩基质扩散、裂隙表面吸附和基质吸附等因素对核素扩散的影响 ,着重探讨了花岗岩基质扩散对核素在裂隙中迁移的影响。建立了相应的二维扩散数学模型 ,运用有限单元法求得其数值解。将数值解、解析解和实验值进行了对比 ,三者较吻合 ,说明所建立的数学模型能很好的反映实际实验条件 ,模型是正确的 ,所进行的数值离散是合理的。由数学模型估算的迁移参数为 :基质域中 ,扩散系数Dp=5 915× 10 -13 m2 /s,孔隙度ε =0 0 19,阻滞系数Rd=1 46× 10 3 ;裂隙中 ,扩散系数Df=1 18× 10 -9m2 /s,等效孔隙度ε =0 87,表面阻滞系数Ra=130 6。
Taking the fresh granite in Yangfang area of Beijing as experimental medium, the experiment of radionuclide diffusion was carried out on the granite column cut with natural fracture surface. The influence of granite matrix diffusion, surface adsorption of fractures and matrix adsorption on the nuclide diffusion was considered. The effect of granite matrix diffusion on nuclide migration was also discussed. The corresponding two-dimensional diffusion mathematical model is established, and its numerical solution is obtained by finite element method. The numerical solution, analytical solution and experimental values are compared. The three are in good agreement, which shows that the established mathematical model can well reflect the actual experimental conditions, the model is correct, and the numerical discretization is reasonable. The migration parameters estimated by the mathematical model are as follows: diffusion coefficient Dp = 5 915 × 10 -13 m2 / s, porosity ε = 0 0 19, and retardation coefficient Rd = 146 × 10 3 in the matrix; The coefficient Df is 1 18 × 10 -9 m 2 / s, the equivalent porosity ε is 0 87, and the surface retardation coefficient Ra is 130 6.