Effect of drying cracks on swelling and self-healing of bentonite-sand blocks used as engineered barriers for radioactive waste disposal
作者机构：School of Civil Engineering and MechanicsLanzhou UniversityLanzhou730000China Key Laboratory of Mechanics on Disaster and Environment in Western China (Lanzhou University)Ministry of EducationLanzhou730000China Civil and Environmental EngineeringUniversity of Wisconsin-MadisonWI53706USA
出 版 物：《Journal of Rock Mechanics and Geotechnical Engineering》 (岩石力学与岩土工程学报（英文版）)
年 卷 期：2024年第16卷第5期
页 面：1776-1787页
核心收录：
学科分类：081401[工学-岩土工程] 08[工学] 0814[工学-土木工程]
基 金：supported by the National Natural Science Foundation of China(Grant No.41972265) the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2021-57) the Gansu Province Science Foundation(Grant No.20JR10RA492) Special thanks to the Environmental Research and Education Foundation for supporting the first author(Y.Tan)through a fellowship for his study at the University of Wisconsin-Madison
主 题：Beishan groundwater chemistry Bentonite buffer Drying cracks High-level radioactive waste(HLW) Self-healing Swelling
摘 要：Experiments were conducted to evaluate the healing of drying cracks in air-dried bentonite-sand blocks after hydration and swelling in groundwater,providing justifications to simplify the protection of blocks prior to installation in a high-level radioactive waste *** groundwater was prepared to represent the geochemistry of Beishan groundwater,and was used to hydrate the blocks during the swelling pressure and swelling strain measurements,as Beishan is the most promising site for China s *** of the surface cracks was recorded by photography,and healing of the internal cracks was visualized by CT images and hydraulic conductivity of air-dried *** results indicate that the maximum swelling pressure and swelling strain are primarily affected by the geochemistry of Beishan groundwater,but not affected by the drying *** maximum swelling pressure and swelling strain of air-dried blocks are comparable to or even higher than the pressure and strain of fresh *** maximum swelling pressure measured in strong(*** ion strength)Beishan groundwater was 44%of the pressure measured in deionized(DI)water,and the maximum swelling strain was reduced to 23%of the strain measured in DI ***,the remained swelling of the blocks hydrated in strong Beishan groundwater was sufficient to heal the surface and internal drying cracks,as demonstrated by the pictures of surface cracks and CT *** hydraulic conductivity of the air-dried block permeated with strong groundwater was comparable(3.7×higher)to the hydraulic conductivity of the fresh block,indicating the self-healing of drying cracks after hydration and swelling in groundwater.A simplified method of protecting the block with plastic wraps before installation is recommended,since the remained swelling of the block hydrated in Beishan groundwater is sufficient to heal the drying cracks.
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