Measurement and modeling of the evaporation rate of loess under high temperature

Abstract

The high-temperature dewatering method has a broad application prospect in loess reinforcement, and the evaporation boundary is a crucial factor in determining the dewatering effect. This study conducts evaporation tests on unsaturated loess columns at high temperatures using a self-made high-temperature evaporation test apparatus to reveal the laws of water and heat transfer and surface evaporation in unsaturated loess under high temperatures. Based on the study's results, high temperatures have a significant driving effect on water. Under high temperatures, the portion of soil near the hot end is rapidly dewatered, forming a drying zone. The presence of an evaporation boundary intensifies the high-temperature dewatering effect. Under hot-end dewatering and surface evaporation, soil water content presents the distribution laws of high at both ends and low in the middle. High temperatures greatly increase surface evaporation. The water content and temperature of surface soil significantly affect evaporation intensity, as do the water gradient and temperature gradient of shallow soil. The evaporation coefficient, defined as the ratio of evaporation intensity to saturated evaporation intensity (potential evaporation intensity), is employed to characterize soil evaporation efficiency. The evaporation coefficient measured under high temperatures is found to be higher than that calculated by the existing models for the evaporation coefficient. A new evaporation coefficient model is built using modifying existing models. The new model comprehensively considers surface and shallow soil temperatures and water contents. Validation results showed that the model can more precisely calculate the evaporation rate of surface soil under the influence of a high-temperature heat source. The research results of this paper reveal the evaporation characteristics of the surface and water migration characteristics inside loess under high temperature, which is helpful for promoting the application of thermal dewatering method in the reinforcement engineering of loess pit slopes.