高放废物地质处置库中非饱和缓冲层的热-水-力耦合数值模拟

Numerical simulation of coupled thermo-hydro-mechanical behavior for engineered barriers in high-level radioactive waste disposal

作为高放废物地质处置库中的缓冲/回填材料,膨润土在核废料放出的热量和周围天然岩体中地下水共同作用下,其热-水-力耦合作用效果对处置库的稳定性、安全性有着极为重要的影响。以非饱和土多场耦合理论为基础,基于ABAQUS有限元分析平台,建立二维轴对称模型,对高放废物地质处置库中膨润土缓冲层的热-水-力耦合过程开展了有限元模拟,给出了处置库近场缓冲层中不同位置的温度、饱和度、竖向应力及位移、孔隙水压力及吸力的分布及变化规律,并重点分析了温度场的影响,通过与已有研究成果的对比,证实了所计算结果的合理性。

Following the need for understanding and quantifying the stability and security of the nuclear waste disposal repository,the coupled thermo-hydro-mechanical behavior of engineered barriers is studied.Bentonites are often envisaged as the main component of engineered barriers.These barriers are always subjected to thermal loading due to the heat emitted by the waste and to hydration from the water coming from the adjacent rock.Based on 2D axisymmetric analysis,finite element modelling of an in-situ large scale experiment is carried out by using ABAQUS.The simulated large scale experiment,called CLAB,is designed in the underground research facility in Sweden.The spatial distribution and variation law of temperature,saturation,pore pressure,suction,vertical stress and displacement in the engineered barrier are investigated.Special attention is given to the temperature effect on saturation,pore pressure,suction,vertical stress and displacement.The results of the finite element modelling of the CLAB experiment are compared with the in-situ measurements and some other computation data using different methods.The proposed modelling and simulating procedures are validated from the good agreement between predictions and in-situ measurements.