Evaluation of hydro-mechano-chemical behaviour of bentonite-sand mixtures

作     者：Wenjing Sun Cheng Liu Diansen Yang Dean Sun Wenjing Sun;Cheng Liu;Diansen Yang;Dean Sun

作者机构：Department of Civil and Energy EngineeringCollege of Environmental Science and EngineeringDonghua UniversityShanghai201620China Institute for the Conservation of Cultural HeritageShanghai UniversityShanghai200444China State Key Laboratory of Geomechanics and Geotechnical EngineeringInstitute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China Shanghai Construction Group Co.Ltd.Shanghai200080China Department of Civil EngineeringSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai200444China 

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：2022年第14卷第2期

页      面：637-652页

核心收录：

学科分类：08[工学] 081401[工学-岩土工程] 0818[工学-地质资源与地质工程] 0814[工学-土木工程] 

基　　金：National Natural Science Foundation of China(Grant No.41977214) the National Key R&D Program of China(Grant No.2019YFC1520500) the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.Z013008)for the financial supports。 

主　　题：Bentonite-sand mixture Hydro-mechano-chemical(HMC)behaviour Salt solution True effective stress 

摘      要：Bentonite-sand mixtures are widely used in engineering barrier of deep geological disposal of high-level radioactive nuclear waste and anti-seepage barrier of civil geotechnical engineering.Under the action of groundwater solution infiltration and external stress,the hydro-mechanical(HM)behaviour of bentonitesand mixtures,i.***.the swelling characteristics and permeability,will change.Once the anti-seepage and filtration effect is weakened or lost,the pollutants will spread to the biosphere.Therefore,it is necessary to study the swelling characteristics and permeability of bentonite-sand mixtures under coupled mechanochemical(MC)effect and to establish corresponding prediction model.For this reason,swelling tests under salt solution with different concentrations are conducted on pure bentonite and its mixtures with 30%,70%and 90%sand contents,the compression tests are carried out on saturated samples,and the saturated permeability coefficient k of the sample under each load is calculated by Terzaghi’s one-dimensional consolidation theory.The concepts of true effective stress pe,montmorillonite void ratio em and critical sand content as are introduced to determine the em-pe relationship and finally the k-em relationship of bentonite-sand mixtures.It is found that when the sand content a
as,the em-pe relationship of the mixture is linear and independent of the salt solution concentration,and when aas,the em-pe relationship of bentonite-sand mixture is bi-linear with the true effective deviatoric stress pesa as the intersection.In addition,the em-k relationship also shows the linear trend when a
as,and the slope of the line increases with the increase of the salt solution concentration.When aas,the k-em relationship will deviate from the linear relationship.Moreover,the larger the sand content is,the farther the deviation is.On the basis of summing the regularity,a model for predicting the HM behaviour of bentonite-sand mixture under the coupled MC effect is proposed.By comparing the swelling and permeability test results with model prediction results of different types of bentonite and its sand mixtures,the predictive model is verified.The study on the HM behaviour of bentonite-sand mixtures under salt solution infiltration and the model establishment can provide experimental and theoretical basis for the design and construction of anti-seepage engineering by bentonite-sand mixtures.