A modified Johnson-Kendall-Roberts contact model for pavement engineering: Consideration of time-dependent surface energy

The Johnson-Kendall-Roberts (JKR) contact model is widely used in the discrete element method to simulate the dynamic behavior of particulate materials by assuming constant surface energy. However, under typical pavement conditions, such as asphalt mixture compaction and moist subgrade drying, particle surface energy varies with temperature and moisture content. This limits the accuracy of the traditional JKR model in capturing the evolution of inter-particle adhesion. To address this limitation, a time-dependent modified JKR contact model was proposed for pavement engineering applications. The modified model's performance was evaluated through a ball–ball pull-off test and validated via a ball gravity loading test based on the conservation of energy. Further, the case studies of pre-compaction and particle dewatering in pavement engineering were conducted using the modified JKR contact model. Results show that, under four different conditions, the compaction impulse increased by 15.57 %, 14.54 %, 13.04 %, and 14.87 %, indicating that the traditional model underestimates the additional compaction energy caused by enhanced adhesion and fails to accurately guide temperature control during compaction. For particle dewatering, the angle of repose decreased from 48.4° to 37.7°, reflecting the transition from a flowable to a stable particle structure. This enables better identification of the optimal construction window during the drying of subgrade materials. Overall, this study enhances the accuracy and applicability of the JKR contact model in pavement engineering by capturing dynamic adhesive behavior more realistically.