酒精湿化法调配压实膨润土缓冲回填材料含水率研究  

Research on the alcohol method to adjust water content of compacted bentonite as buffer/backfill material

作　　者：彭宇 张虎元[1] 周光平 谭煜 PENG Yu;ZHANG Hu-yuan;ZHOU Guang-ping;TAN Yu(Key Laboratory of Mechanics on Disaster and Environment in Western China,Ministry of Education,Lanzhou University,Lanzhou,Gansu 730000,China;Department of Civil and Environmental Engineering,The Hong Kong Polytechnic University,Hong Kong,China)

机构地区：[1]兰州大学西部灾害与环境力学教育部重点实验室,甘肃兰州730000 [2]香港理工大学土木与环境工程学院,中国香港

出　　处：《岩土力学》2024年第1期235-244,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金面上项目(No.41972265)。

摘　　要：压实膨润土砌块在我国高放射性废物处置中发挥着缓冲回填工程屏障的作用。然而,膨润土材料塑性极强,水分极易拌和不均,易导致压实砌块干缩开裂,显著降低了砌块质量。提出一种采用酒精代替纯水来湿化膨润土的新方法,以提高压实膨润土质量。对比喷水法,酒精湿化法中酒精浓度设计在5%~35%间。通过分析膨润土与酒精混合物的混合效率、黏附质量损失率、混合物中团聚体的含量、压实样干缩前后强度、干缩裂纹规律、干燥效率、膨胀性等指标综合评价酒精湿化压实膨润土样的适用性。试验结果表明:在相同含液率情况下,随酒精浓度增大,所得膨润土样的混合效率明显提高,黏附质量损失率及团聚体含量明显降低;压实样内团聚体与干缩裂纹及试样质量间具有较好对应关系。此外,酒精湿化法所得压实样在压实方向密度分布更均匀,干缩裂纹数量及宽度明显变小,风干试样剪切强度及膨胀性均与加纯水试样较为接近,压实样均匀性与完整性明显提高。新方法及相关成果可供我国高放废物缓冲回填砌块制备参考。Compacted bentonite is a crucial material used in high-level waste engineering barriers as a buffer/backfill material.However,the high plasticity of bentonite and uneven distribution of water can result in drying shrinkage of the compacted bentonite,which negatively impacts the quality of buffer/backfill blocks.To address this issue,a new method called the alcohol method has been proposed as an alternative to the traditional water spray method.In the alcohol method,the ethanol content ranges from 5%to 35%,unlike the water spray method.Several factors were considered to evaluate the feasibility of the alcohol method in adjusting the water content of compacted bentonite.These factors included mixing efficiency,mass loss rate,agglomerate content,strength,shrinkage cracks of compacted samples,drying efficiency,and expansibility.The results demonstrated that as the ethanol content increased,at the same liquid content the mixing efficiency significantly improved,while the mass loss rate and agglomerate content decreased noticeably.Relationships between agglomerates,dry-shrinkage cracks,and the quality of compacted samples were also observed.The compacted samples produced using the alcohol method exhibited more homogeneous soil density in the compacted direction and significantly reduced dry-shrinkage cracks compared to samples produced using the water spray method.Additionally,the shear strength and expansion characteristics of air-dried samples adjusted by the alcohol method were similar to those adjusted by the water spray method.The alcohol method,along with the findings from this study,provides valuable insights for the production of buffer/backfill materials in high-level waste disposal.

关 键 词：压实膨润土 缓冲回填材料 酒精湿化法 含水率 团聚体 

分 类 号：TU411[建筑科学—岩土工程]