NUMERICAL MODELLING AND SIMULATION OF COUPLED THM PROCESSES IN TASK_D OF DECOVALEX_IV
NUMERICAL MODELLING AND SIMULATION OF COUPLED THM PROCESSES IN TASK_D OF DECOVALEX_IV
复制标题
DOI：
--
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
L. Xiaoyan
中科院分区：
文献类型：
--
作者：
L. Xiaoyan
DECOVALEX项目的目的（开发耦合模型及其与实验的验证）是集中在各种耦合的热-水-机械（THM）和地球化学过程中发生在近场的高活性放射性废物处置设施，一个示范工程屏障的建设的可行性，以及它们如何影响性能评估的作用，放射性废物处置。DECOVALEX_IV项目的Task_D包括对FEBEX型和Yucca山项目型两个通用处置库的长期耦合过程（长达1×104年）进行预测分析，以供比较。为了更好地理解耦合THM过程及其对系统行为的影响，本文提出了一个严格的处理非等温流动和变形的理论在非饱和多孔介质。用系统的宏观方法导出了以质量守恒、能量守恒、平衡方程、达西定律、傅立叶定律为基础的控制方程。三相（固体、液体和气体）中的每一相都被视为一个独立的连续体，具有自己的运动学。四个成分（固体，水，蒸汽和干燥的空气）被确定。建立了四个相互独立但又相互重叠的模型：（1）考虑流体有效应力、热应力和膨润土饱和膨胀压力的固体变形模型，（2）考虑蒸发或凝结过程中水与水蒸气之间质量交换的水气流动模型，（3）考虑在假定的均质孔隙气相中水蒸气与干空气相对运动的水蒸气分子扩散和平流模型，（4）考虑水蒸气与干空气的相对运动的水蒸气分子扩散和平流模型。（4）考虑三相不等温的非平衡局部热过程的传热模型。在此基础上，根据Task_DBMT（Benchmark Test）的要求，建立了实用模型，并编制了程序，模拟了1×106年的THM耦合过程。仿真结果在2005年昆明举行的Task_D工作组会议和DECOVALEX_IV第三次研讨会上得到了验证。与其他国家的参与团队的结果有很好的一致性。
The purposes of the DECOVALEX project(development of coupled models and their validation against experiments) are focused on the various coupled thermo-hydro-mechanical(THM) and geochemical processes occurring in the near field of a high activity radioactive waste disposal facility,of a demonstration for the feasibility of the construction of engineered barriers,and of how they affect the role of performance assessment for radioactive waste disposal. Task_D of the DECOVALEX_IV project includes predictive analysis of the long-term coupled processes(up to 1×104 years) in two generic repositories——FEBEX type and Yucca Mountain Project type for comparison. To better understand the coupling THM processes and their influences on the system behaviours,this paper presents a rigorous treatment of the theory of non-isothermal flow and deformation in unsaturated porous media. The governing equations based on the conservation equations of mass and energy and the equations of equilibrium,Darcy′s law,Fourier′s law are derived by using a systematic macroscopic approach. Each of the three phases(solid,liquid and gas) is viewed as an independent continuum, endowed with its own kinematics. Four constituents(solid,water,vapour and dry air) are identified. Four separate but overlapping models are developed as follows:(1) deformation model for solid considering the fluid effective stress, thermal stress,and bentonite saturation swelling pressure;(2) flow model for water and gas considering the mass exchange between water and vapour in evaporation or condensation processes;(3) vapour molecular diffusion and advection model considering the relative movement of vapour to dry air in presumed homogenous pore gas phase;and (4) heat transfer model considering the non-equilibrium local thermal processes that three phases are not at a same temperature. Based on above equations,practical models are developed according to the given Task_D BMT(bench mark test) request,and the codes are programmed to simulate coupled THM processes in 1×106 years with Task_D BMT set-up. Simulation results are shown and verified in Task_D force meeting and the third workshop of DECOVALEX_IV in Kunming(2005),China. There is a good agreement with results of participant teams from other countries.