Study on compression performance of bentonite block wall and its constitutive model
With the progress of three-stage strategy of the deep geological repository for high-level radioactive waste in China,the research on the mechanical properties and failure characteristics of the block structure of the buffer/backfill material can provide basic data for the design of the buffer/backfill material and the surface stacking and storage of the blocks.In this paper,bentonite blocks are manufactured using Gaomiaozi sodiumbentonite powder by suitable pressing path,and the dry masonry method is used to build block walls.The interface performance test and axial compression test between block units are designed and carried out,the relationship between the interface shear strength and shear displacement between block units is obtained,and the stress-strain curve and failure mode of block wall are analyzed.The test results show that the deformation and failure of block wall experience characteristic deformation,localized crack propagation,vertical crack penetration,instability failure and residual deformation.The first crack of block wall appears in a single block unit,which indicates that the quality of block unit is one of the important factors to control the engineering performance of block wall.The constitutive models of SHI Chuxian,ZHU Bolong,TURNSEK,HODGKINSON and ZHONG Jiqing are compared and analyzed based on the test results.It is found that the parameters of ZHONG Jiqing model modified with the test data in the pre-peak ascent curve section,resulting in a theoretical stress-strain curve in good agreement with the experimental data.
high-level radioactive waste disposalbuffer/backfill materialbentonite block wallmechanical propertyconstitutive model
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