Numerical thermo-hydro-mechanical modeling of compacted bentonite in China-mock-up test for deep geological disposal

The China-mock-up test is to evaluate the performance of the compacted Gaomiaozi （GMZ） bentonite under coupled thermo-hydro-mechanical （THM） conditions in deep geological disposal. A numerical study of the test is conducted in this paper. The principal THM characteristics of the bentonite are presented at first. A THM model is then presented to tackle the complex coupling behavior of the bentonite. The model of Alonso-Gens is incorporated to reproduce the mechanical behavior of the bentonite under unsaturated conditions. With the proposed model, numerical simulations of the China-mock-up test are carried out by using the code of LAGAMINE. The time variations associated with the temperature, degree of saturation, suction and swelling pressure of the compacted bentonite are studied. The results suggest that the proposed model is able to reproduce the mechanical behavior of the bentonite, and to predict moisture motion under coupled THM conditions.

工程尺度缓冲材料热-水-力多场耦合数值模拟研究

缓冲材料作为填充在废物罐与地质体之间重要的人工屏障,对高放废物处置库的长期安全至关重要。以工程尺度缓冲材料热-水-力多场耦合大型模型试验系统(China-Mock-up)为研究对象,采用有限元数值模拟软件LAGAMINE,考虑试验过程中复杂的边界条件与材料属性,实现了近5 a试验数据的定量模拟。模拟结果可准确预测试验系统内部不同特征点温度随室温周期性波动及线性增长这一动态变化规律;能够较好反映不同特征点相对湿度随时间的行为演化趋势,在加热器附近区域呈现出先干燥后饱和的现象,远离加热器区域则逐渐增大;模拟的总应力与实测试验数据间表现较好地一致性,能够反映试验台架内部不同特征点的总应力随时间逐渐增大这一演化过程。揭示了多场耦合条件下缓冲材料(膨润土)温度、湿度及应力的相互作用关系,为深入认识处置库环境下缓冲材料行为演化特征提供了重要的参考依据。