考虑溶质浓度影响的热-水-应力-迁移耦合模型及数值模拟

高放射性核废料地质处置库围岩中地下水的密度因溶质浓度不同而发生变化,这将影响到饱和-非饱和孔隙介质中近场和远场的热-水-应力耦合过程, 同时温度场、应力场也要对地下水中的核素及矿物质迁移产生作用.考虑这两个因素,建立和引入了相关的应力平衡方程、水连续性方程、能量守恒方程和渗透迁移方程,并研制出了对应分析孔隙介质中热-水-应力-迁移耦合问题的二维有限元程序.通过对一个假定的核废料地下处置库在核素泄漏后多场耦合过程的数值计算,考察了近场围岩中的温度、应力、孔隙水压力、核素浓度的分布及随时间的变化.结果初步显示了所建模型及程序可模拟热-水-应力-迁移耦合现象,因而具有一定的实用性.

Model and numerical simulation for coupled thermo-hydro-mechanical-migratory processes considering influence of solute concentration

The density of groundwater in the surrounding rockmass of a geological disposa/ repository of high-level radioactive nuclear waste varies with the solute concentration, which will influence the thermo-hydro-mechanical processes in near field and far field of the saturated-unsaturated porous media. At the same time the temperature field and the stress field will also exert actions on the migratory of nuclides and solutes in groundwater. Considering these two factors the relevant momentum equilibrium equation, the continuity equation for water, the energy balance equation and the percolation and migration equation are established and introduced; and a 2D code of finite element method is developed for analyzing coupled thermo-hydro-mechanical-migratory phenomena in porous media. Through a numerical computation for the multi-field coupling progress after nuclide leakage in an assumed nuclear waste repository, the distribution and change of the temperature, stresses, pore pressures and nuclide concentrations in the near field are investigated. The results show that the established model and FEM code can be used to simulate coupled thermo-hydro- mechanical-migratory phenomena, so as to have certain practicality.