Temperature effects on unsaturated hydraulic property of bentonite-sand buffer backfilling mixtures

Abstract

The influence of temperature on the engineered properties of bentonite-sand mixtures (B/S) is of major concern in the design of engineered barriers in underground repositories for high-level radioactive waste disposal. We experimentally studied the influence of temperature on soil unsaturated hydraulic properties related to water holding capacity and permeability of GMZ B/S in China. The vapor equilibrium method and water infiltration apparatus were used to measure the soil water characteristic curve (SWCC) and unsaturated hydraulic conductivity (k _u). The results show that the SWCC under different temperatures from 20 °C to 60 °C tends to be the same. Temperature influence on unsaturated permeability is more relevant at low suctions, no clear effect is detected below a degree of saturation of 74%, and experimental data show that temperature dependence on unsaturated permeability is small.

Keywords

high-level radioactive waste disposal / engineered barrier / temperature / soil water characteristic curve / unsaturated hydraulic conductivity

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