Deciphering the dynamics of debris flows through basal stress responses in model experiments

Abstract

Comprehending the basal stress and stress fluctuations of debris flows at their boundaries and understanding how these effects influence the dynamics of debris flows are crucial for disaster reduction. In this study, a series of physical model experiments were conducted with varying initial conditions to investigate the basal stress responses and dynamic behaviors of debris flow. Experimental results show that the basal stress at the contact surface of debris flow is significantly influenced by material composition and slope. Specifically, an increase in gravel fraction and slope lead to enhanced basal normal and shear stresses, whereas higher water content exerts the opposite effect. Additionally, the fluctuating stress in normal stress is primarily influenced by material composition, particularly the proportion of coarser materials. Notably, particle agitation is linked to the inertial stress within the debris flow, exhibiting a positive correlation. Enhanced particle agitation facilitates the sparse and vigorous movement of debris flow, further promoting its development. Lastly, a method for predicting flow resistance in debris flow based on macro-scale stress fluctuation monitoring is proposed, providing valuable insights for disaster prevention and mitigation strategies.