Anisotropic swelling pressures of compacted GMZ bentonite infiltrated with salt solutions

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外文摘要：In the high-level radioactive waste(HLW)deep geological repository,bentonite is compacted uniaxially,and then arranged vertically in engineered barriers.The assembly scheme induces the initial anisotropy,and with hydration,it develops more evidently under chemical conditions.To investigate the anisotropic swelling of compacted Gaomiaozi(GMZ)bentonite and the further response to saline effects,a series of constant-volume swelling pressure tests were performed.Results showed that dry density enhanced the bentonite swelling and raised the final anisotropy,whereas saline inhibited the bentonite swelling but still promoted the final anisotropy.The final anisotropy coefficient(ratio of radial to axial pressure)obeyed the Boltzmann sigmoid attenuation function,decreasing with concentration and dry density,converging to a minimum value of 0.76.The staged evolution of anisotropy coefficient was discovered,that saline inhibited the rise of the anisotropy coefficient(Δδ)in the isotropic process greater than the valley(δ1)in the anisotropic process,leading to the final anisotropy increasing.The isotropic stage amplified the impact of soil structure rearrangement on the macro-swelling pressure values.Thus,a new method for predicting swelling pressures of compacted bentonite was proposed,by expanding the equations of Gouy-Chapman theory with a dissipative wedge term.An evolutionary function was con-structed,revealing the correlation between the occurrence time and the pressure value due to the structure rearrangement and the former crystalline swelling.Accordingly,a design reference for dry density was given,based on the chemical conditions around the pre-site in Beishan,China.The anisotropy promoted by saline would cause a greater drop of radial pressure,making the previous threshold on axial swelling fail.

外文关键词：

HLW deep geological repositoryCompacted GMZ bentoniteAnisotropic swelling pressureMulti-scale structureSaline effect

作者：

Jing Ma、Yong-Gui Chen、Ling-Yan Jia、Wei-Min Ye、Dong-Bei Wu、Qiong Wang

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作者单位：

Department of Geotechnical Engineering,College of Civil Engineering,Tongji University,Shanghai,200092,China

State Key Laboratory of Disaster Reduction in Civil Engineering,College of Civil Engineering,Tongji University,Shanghai,200092,China

School of Chemical Science and Engineering,Tongji University,Shanghai,200092,China

基金：

National Science Fund for Distinguished Young Scholars of ChinaInnovation Program of Shanghai Municipal Education CommissionFundamental Research Funds for the Central Universities,and Top Discipline Plan of Shanghai Universities-Class Ⅰ

项目编号：

421257012023ZKZD26

出版年：

2024

DOI：

10.1016/j.jrmge.2024.01.024

岩石力学与岩土工程学报(英文版)

中国科学院武汉岩土力学所中国岩石力学与工程学会武汉大学

岩石力学与岩土工程学报(英文版)

CSTPCD

影响因子：0.404

ISSN：1674-7755

年,卷(期)：2024.16(9)