Effect of complex climatic and wheel load conditions on resilient modulus of unsaturated subgrade soil

Abstract

Resilient modulus (Mr) is a fundamental mechanical property vital for assessing the resistance of pavement structures to cyclic vertical loads. It has played a pivotal role in pavement design and has been instrumental in predicting pavement responses and fatigue life. The Mr of subgrade soil is affected by a multitude of factors, including stress, moisture, and temperature conditions, all of which interact to define the response of the soil. This research investigated the effect of complex climatic conditions on Mr with a particular focus on areas experiencing significant seasonal changes in snowy cold regions like Hokkaido, Japan. Previous studies have proposed predictive models for Mr, incorporating the concept of matric suction, to account for moisture conditions. However, these models have rarely considered suction hysteresis in the soil–water characteristic curve (SWCC) or the effects of wheel loading on frost-susceptible subgrade soil during different seasons. In this study, a series of Mr tests were conducted on two types of subgrade soil under various climatic and wheel loading conditions. The test results promise to enhance our understanding of the complex interplay of climatic and stress conditions on Mr of standard sand and frost susceptible subgrade soil along different drying and wetting paths, particularly in regions with significant seasonal variations.