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.