Particle Size-Dependent Cohesion of Sands: Insights from a Fluidized Bed Approach

OpenAlex İngilizce

Erosion dynamics in channels are significantly influenced by the interaction between frictional forces among sand particles and hydrodynamic shear stresses exerted by flowing water. Understanding how particle size affects cohesion and resistance to entrainment is crucial for accurate sediment transport modeling and erosion control. This study quantifies the mechanical cohesion characteristics of sand particles across different size classes using a fluidized bed approach. Cohesion was assessed by measuring the pressure drop (ΔP) at the fluidization point (ΔPf) and the corresponding flow velocity (Vf) through sensor-based precise measurements. Five sand classes—very coarse sand (VCS), coarse sand (CS), medium sand (MS), fine sand (FNS), and very fine sand (VFNS)—were tested under controlled hydraulic conditions. Results indicate that cohesion (Co) decreases with decreasing particle size, confirming the strong correlation between particle size and internal friction. The highest cohesion values were observed in VCS (23268 Pa m⁻¹), while VFNS exhibited the lowest (8881 Pa m⁻¹). Conversely, the fluidization velocity followed an inverse trend, with coarser particles requiring higher velocities for entrainment. These findings align with previous research on sediment stability and suggest that finer sands are more prone to mobilization under lower shear stresses. Additionally, findings highlight implications for channel stability and erosion control strategies, particularly in environments where sediment mobilization influences hydrological and geomorphological processes. The integration of these findings into prevailing models, such as the Revised Universal Soil Loss Equation (RUSLE) and the Water Erosion Prediction Project (WEPP), facilitates a more accurate assessment of soil resistance to detachment and transport. This incorporation could facilitate more precise predictions of sediment transport dynamics, particularly in contexts where particle size and friction forces are pivotal factors. It is acknowledged that laboratory experiments provide precise measurements; nevertheless, it is imperative that they be meticulously evaluated and further validated in natural field conditions.