Deformations of bentonite-sand mixture without lateral confining pressure subject to high suctions changing

Ashikaga University, Department of Civil Engineering, Ashikaga Tochigi, Japan

^* email address: nishimura.tomoyoshi@g.ashikaga.ac.jp

Abstract

Generation of electricity in nuclear power plants have supplied further energy to society in the world, and remain arising of radioactive waste as results of performance industry with activity. In fact, all of radioactive waste encourage some categories types as following; two most important points are high-level waste (HLW) and low- and intermediate-level waste (LLW). To end disposal completely, every country operated Nuclear Energy plant foresees further deep geological repository. This study conducted out measurement of deformations due to changing suction, which were volume change, axial strains and radial strains. Used triaxial compression apparatus was improved to be possible controlling suction for air flow circulation, and measured both axial and radial strains and variations of mass under drying-wetting cyclic in suction. Required suction rage is from 2.8 MPa to 296 MPa, and it corresponds to from 98.0 % to 11.0 % in relative humidity. Axial strains and radial strains for all of specimens have described obviously the shrinkage phenomena due to drying and wetting cyclic process regard to suction potential, and bentonite-sand mixture specimens are statically compacted. Axial strains compare that is larger than radial strains regard to all applied suctions. Subsequently, changing of void ratio was classified into two categories, which one was elastic components and other one was plastic component, and elastic component in void ratio was remaining larger than plastic component for high suction ranges.