| Summary: | 碩士 === 國立中央大學 === 土木工程研究所 === 87 === Abstract
(key words: buffer material, hydraulic conductivity, swelling pressure, thermal conductivity)
Radioactive wastes are required to be isolated from the environment to prevent possible contamination. The disposal concept presently being considered is " deep geological disposal ". In an underground disposal site, the radioactive wastes are encapsulated in containers surrounded by a buffer material and the excavation backfilled with a mixture of clay and aggregate. The study aims at creating an appropriate composition of the buffer material with satisfactory performance and characterizing the engineering properties of buffer material for underground radioactive waste disposal.
Synthetic clays with plastic index of 30,82,and 214 were mixed with crushed Andesite-aggregate having top size of 2.24 mm. We use clay proportion with 25% and 50%. In order to meet the stringent requirements of buffer material, a series of tests including compaction characteristic, hydraulic conductive, swelling pressure, thermal conductivity, and shrinkage due to drying were conducted on clay-sand mixtures to evaluate the physical properties of buffer material.
The results indicate that the hydraulic conductive of buffer material is lower when the PI is 330 and the proportion of clay is 50%. The kind and proportion of clay both influence the hydraulic conductive, and the kind of clay (different PI) effects obviously. Including the proportion and the PI of clay both cause thermal conductivity lower. Reducing clay content and the PI cause lower swelling pressure and shrinkage due to drying
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