热-水-应力耦合条件下三项因素对核素迁移影响的有限元分析  

Finite element analysis of effects of three factors on nuclide migration under condition of coupling thermo-hydro-mechanical

作　　者：张玉军[1] 

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,武汉430071

出　　处：《岩土力学》2008年第10期2599-2605,2618,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.50578171);国家自然科学基金重点项目(No.50239070)资助

摘　　要：目前在放射性核素随地下水迁移的研究中还很少涉及温度场和应力场的影响。针对这一问题,引入渗透迁移方程,将所开发的饱和—非饱和孔隙介质中热-水-应力耦合弹塑性模型及其二维有限元程序进行了扩展和改进,使之可以同步地对温度场、渗流场、应力场和放射性核素浓度场的变化进行解析。对一个假想的核废料处置库算例,通过分别改变影响地下水中核素迁移的3个因素:渗透系数、分配系数和分子扩散系数,考察了在热-水-应力-迁移耦合作用条件下近场放射性核素浓度的分布及变化,从而认识到:当缓冲层的渗透系数小到一定程度后,缓冲层中核素迁移基本不再受渗流场的影响;缓冲层分配系数越小,分子扩散系数越大,核素迁移越快。Up to now the influences of temperature field and stress field on the migration of radioactive nuclide with groundwater have been studied rarely. Against this problem, the elasto-plastic model and the relative 2D FEM code have been extended and improved for analysis of coupled thermo-hydro-mechanical processes in saturated-unsaturated porous media developed by introducing percolation and migration equation, so that the code can be used for solving the temperature field, flow field, stress field and nuclide concentration field at the same time. Then a computation example of an assumed nuclear waste repository, in which different values of permeability, distribution coefficient and molecular diffusion coefficient of buffer material are used respectively, the distributions and changes of nuclide concentration in the near field are investigated under the condition of coupled thermo-hydro-mechanical-migratory. The results show that the transport of nuclides in buffer are not influenced by the flow field nearly when the permeability of buffer is low to a certain extent; the less the distribution coefficient and the greater the molecular diffusion coefficient are, the faster the nuclide transport is.

关 键 词：岩土力学 热-水-应力耦合 核素迁移 影响因素 二维有限元分析 

分 类 号：TB115[理学—数学] P641.3[理学—应用数学]