Investigating and predicting the temperature effects of permeability for loess

Abstract

Temperature is one of the key factors affecting the permeability of water flow in loess, influencing its stability and, consequently, its geohazard potential. The traditional temperature calibration formula(TTCF) is widely used in the literature for calculating the permeability at some temperature, based on the permeability at 20 °C. However, its suitability has not been verified, especially for water flow in loess. The influence of temperature on the permeability of loess and the suitability of the TTCF were examined using samples of the late-Pleistocene Malan loess, the most widely distributed loess in the Chinese Loess Plateau, as the subject. The temperature dependency of the saturated permeability of remolded loess was investigated using the constant head permeability test method over a temperature range of 0 to 40 °C. The results show that the permeability of remolded loess increases with temperature, but in a nonlinear manner. Between 0 and 4 °C, although the changes are small, and at around 25 °C, there may be an important change in the soil's structure. We found that the measured values of loess permeability deviate strongly from those calculated by the TTCF, especially over the temperature range 0 to 4 °C and > 25 °C. New formulas for the calibration of temperature effects on the permeability of loess have subsequently been developed. Also, an empirical model for predicting the saturated hydraulic conductivity was inferred, which can satisfactorily reflect the temperature and compactness effects on permeability. The results of this study may be employed for projecting the effects of temperature changes into loess engineering and in assessing geohazard potential.