29 / 2024-08-26 14:10:33

EXPERIMENTAL STUDY ON COMPARATIVE TEST OF ARTIFICIAL COHESIVE SEDIMENT BASED ON RHEOLOGICAL CHARACTERISTICS

Artificial cohesive sediment,rheological properties,yielding process,structural recovery,comparison method

Session 24 - Estuaries and coastal environments stress - Observations and modelling

In muddy coastal regions, cohesive sediment transport impacts coastal morphology evolution, marine environmental protection and marine engineering construction. The natural cohesive sediment and the artificial cohesive sediment are taken as the main research object. Rheological method is used to carry out rheological experiment of cohesive sediment, reveal the structural yielding and recovery process of cohesive sediment under steady and oscillatory shear load, verify the feasibility of using artificial cohesive sediment instead of natural mud for rheological tests, analyze the influence of multiple factors on the structural yielding and recovery process of artificial cohesive sediment. Natural and artificial cohesive sediment have similar structural yielding and recovery processes. Under steady and oscillatory shear loads, the fluidization of both natural and artificial cohesive sediments occurs. Rheological behavior can be divided into three regions: solid-like region, solid-fluidic region and liquid region. In addition, after being subjected to pre-shear load, the normalized storage modulus of natural and artificial cohesive sediments shows a rapid increase during the initial stage, followed by a progressively slower increase over time until it ultimately reaches an equilibrium state. The normalized equilibrium storage modulus decreases first and then increases with the increase of pre-shear load. The influence factors such as water content can significantly change the structural yielding process of artificial cohesive sediment. The artificial cohesive sediment samples with low water content or quartz sand content have higher static and fluidic yield stresses. Even if 0.1% EPS is added to the artificial cohesive sediment sample, the yield stresses of the sample will increase by one order of magnitude. However, with the increase of EPS content, the yield stress of the sample does not change monotonously. The frequency does not affect the static and fluidic yield stress of cohesive sediment, but the larger the frequency, the lower the fluidic critical amplitude strain, that is, the sample is more easily to fluidization.