吸–脱湿过程中GMZ膨润土颗粒的水–力特性

doi:10.13722/j.cnki.jrme.2023.0418

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摘要膨润土颗粒材料因具有制备成本低、运输方便、施工工艺简单等优点，被看作是高放废物深地质处置库一种新型的缓冲回填材料。以我国高庙子(GMZ)膨润土为对象，采用气相平衡法开展吸力控制下膨润土颗粒的吸–脱湿试验，结合MIP微观测试技术，探究吸–脱湿过程中膨润土颗粒的持水特性、体变特性及微观结构特征。试验结果表明：(1) 膨润土颗粒的吸湿/脱湿持水曲线在低吸力阶段基本一致，而在高吸力阶段呈现迟滞现象；(2) 吸–脱湿过程中膨润土颗粒湿化膨胀、干化收缩，并在高吸力段产生不可恢复的塑性变形；(3) 吸湿过程中，膨润土颗粒集合体间孔隙体积增加，孔隙分布曲线由“单峰”型向“双峰”型发展，而在后续脱湿过程中，集合体间孔隙无法完全恢复，孔隙分布曲线呈“双峰”特征；(4) BExM模型可较好地模拟吸–脱湿过程中膨润土颗粒的胀缩变形特征，并能反映水化过程中颗粒混合物集合体内孔隙、集合体间孔隙和颗粒间孔隙的演化规律。

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	张召1
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	叶为民1
	王琼1
	陈永贵1
	张可能2

关键词 ：土力学, 膨润土颗粒, 持水曲线, 胀缩变形, 孔隙尺寸分布, 本构模型

Abstract：Bentonite pellets have been recognized as a new form of buffer/backfilling material in the construction of a multi-barrier system for high-level waste(HLW) disposal，which is primarily due to their cost-effectiveness in production，easy transportation and convenient installation. In this study，a series of suction-controlled hydration/unhydration tests and microscopic tests were performed on GMZ bentonite pellets using the vapor equilibrium technique. The objective was to investigate the water retention property，volume-change behavior，and micro-structural evolution of the pellets. The results demonstrated that the wetting/drying water retention curves of single bentonite pellet exhibited a hydraulic hysteresis at high-suction stage，but this phenomenon was less pronounced at low-suction stages. Bentonite pellets underwent a expansion with the absorption of water and a shrinkage with the loss of water during a wetting/drying cycle. This process led to the generation of plastic deformation at the high-suction stage. As inter-aggregate pores increased during the wetting process，the pore size distribution curve of bentonite pellets gradually transitioned from a unimodal porosity to a bimodal one. Even during the subsequent drying process，the curve continued to exhibit a bimodal porosity because the inter-aggregate pores were unable to fully recover. The BExM model effectively reproduced the swelling or shrinking behaviors of bentonite pellets during wetting and drying processes. Additionally，it was also used to analyze the changes of multi-scale pores within the bentonite pellet mixture，including the examination of intra-aggregate pores，inter-aggregate pores，and inter-pellet pores.

Key words： soil mechanics bentonite pellet water retention curve swelling/shrinking deformations pore size distribution constitutive model

引用本文:

张召1，2，叶为民1，王琼1，陈永贵1，张可能2 . 吸–脱湿过程中GMZ膨润土颗粒的水–力特性[J]. 岩石力学与工程学报, 2024, 43(S2): 4062-4071.
ZHANG Zhao1，2，YE Weimin1，WANG Qiong1，CHEN Yonggui1，ZHANG Keneng2. Hydro-mechanical behavior of GMZ bentonite pellet upon wetting and drying. , 2024, 43(S2): 4062-4071.

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https://rockmech.whrsm.ac.cn/CN/10.13722/j.cnki.jrme.2023.0418 或 https://rockmech.whrsm.ac.cn/CN/Y2024/V43/IS2/4062

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