温控下高压实膨润土持水特性及预测研究

RESEARCH ON THE WATER RETENTION CHARACTERISTIC AND PREDICTION OF COMPACTED BENTONITE UNDER CONTROLLED TEMPERATURE

高庙子膨润土是我国核废料深地质处置的首选材料。作为缓冲密封材料,在使用过程中,会受到核素衰变放热的影响而改变土的持水特性、渗透性和力学特性,其工作性能也随之改变。为研究高温下高庙子膨润土的持水特性,文中采用在80℃侧限条件下进行实验研究。实验采用渗析法和水汽平衡法来控制吸力,测得在不同吸力点的含水量,从而得出土水特征曲线。对于特定吸力点的土样进行压汞试验,分析不同吸力点的孔隙特点,并由压汞试验得到PSD曲线来预测其土水特征曲线,并在PSD预测中考虑温度影响。最终将PSD预测曲线与实测曲线对比研究,发现考虑温度的PSD预测比较接近于真实的土水特征曲线。

GMZ bentonite is considered as the first choice of Chinese buffer materials providing base for high level radioactive nuclear waste geological repository. As a sealing and buffer material, it will be effected by the decay heat of the nuclear waste. Then, the retention capacity, permeability and mechanical behavior of the compacted GMZ bentonite will be changed as the temperature. For studying on the influence of temperature on the retention capacity of the GMZ bentonite, the laboratory study is carried out under isochoric and 80℃ condition. The osmotic technique and vapor equilibrium technique were used for controlling suction. Through the laboratory study, including the measurement of soil-water characteristic curves （SWCC）, and the mercury intrusion porosimetry（MIP）test, the paper studies on the retention capacity and characteristic of pore at differ- ent suction. Finally, the SWCC is predicted by the MIP results. If considering the effects of temperature, the predicted SWCC is more similar to the testing curve.