Numerical Simulation for Temperature Field and Salt Heave Influential Depth Estimation in Sulfate Saline Soil Highway Foundations

Abstract

Highway foundation cracking as a result of salt heave is an issue in regions with wide saline soil distribution. The aim of this study is to estimate the influential depth of salt heave on highway foundations based on the temperature field and heave-initiation and heave-sensitive ranges. The temperature in highway foundations was measured using field-installed geothermometers, and numerical simulation using the finite-element method (FEM) was conducted to estimate the temperature field in highway foundations. Temperatures under the highway centerline and shoulders were investigated. Three types of soil (lean clay, eolian sand, and sand gravel) and three levels of salinity (0%, 1.3%, and 3.0%) were included for analysis. The results showed that the influential depth owing to air temperature change under the shoulder was greater than that under the centerline. The temperature change in the subgrade lagged behind the air temperature change. Numerical simulation using the FEM was able to predict the temperature change in the subgrade associated with the air temperature change. Salinity and soil type had a significant influence on the temperature field in the subgrade. The influential depth of salt heave on highway foundations was determined based on the temperature field and the salt heave properties of the soils. This study provides a good reference for the salt heave characteristics of saline soil highway foundations.