Investigation on compression behaviour of highly compacted GMZ01 bentonite with suction and temperature control
Résumé
In this paper, an oedometer with suction and temperature control was developed. Mechanical compaction tests have been performed on the highly compacted GMZ01 bentonite, which has been recognized as potential buffer/backfill material for construction of Chinese high-level radioactive waste (HLW) geological repository, under conditions of suction ranging from 0 to 110 MPa, temperature from 20 to 80 degrees C and vertical pressure from 0.1 to 80 MPa. Based on the test results, suction and temperature effects on compressibility parameters are investigated. Results reveal that: (1) at high suctions, heating induced an expansion, while contraction is induced by heating at low suctions. The thermal expansion coefficient of GMZ01 bentonite measured is 1 x 10(-4) degrees C-1; (2) with increasing suction, the elastic compressibility kappa and the plastic compressibility lambda(s) of the highly compacted GMZ01 bentonite decrease, while the preconsolidation pressure increases markedly; (3) with increasing temperature, the elastic compressibility of compacted GMZ01 bentonite changes insignificantly, while the plastic compressibility lambda(s) slightly decreases and the yield surface tends to shrink. Crown Copyright (c) 2012 Published by Elsevier B.V. All rights reserved.