Intrusion behaviors of highly compacted bentonite into host-rock#br# fractures in a HLW disposal repository
HUANG Yiyi1，2，CHEN Bao1，2
(1. College of Civil Engineering，Tongji University，Shanghai 200092，China；2. Key Laboratory of Geotechnical and Underground Engineering of the Ministry of Education，Tongji University，Shanghai 200092，China)
Abstract：The intrusion-flushing behaviour of compacted bentonite buffer/backfill materials may produce uncertainties to the long-term security of HLW disposal repositories. In this paper，concentrating on the issue of bentonite intrusion，the intrusion behaviour of highly compacted Gaomiaozi(GMZ) bentonite into fractures was investigated using an intrusion instrument，and five groups of tests with different parametric combinations of the fracture aperture(df) and the initial dry density( )were performed. The evolution curves of the intrusion distance and the swelling pressure were obtained，the mass loss of the core bentonite was analysed，and the influence of df and on the intrusion behaviour of bentonite was discussed. The results show that both df and have great influence on the overall intrusion velocity，the total intrusion amount and the state variation of the core bentonite. The values of the slope of the linear portion of the intrusion distance evolution curve，A，reflecting the overall intrusion velocity，in the cases of the maximum df and the maximum are respectively 2.5 times and 2.1 times as big as those in the cases of the minimum df and the minimum ，and correspondingly，the total intrusion amount values are 3.1 times and 2.8 times respectively. The swelling pressure drop percentages corresponding to the maximum df and the maximum are respectively 53.1% and 48.6%，which are much higher than 3.6% and 17.6% corresponding to the minimum df and the minimum . It can be concluded that a larger df or a larger will produce a stronger outflow of bentonite mass.
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2019, Vol. 38 
