Laboratory study on submarine debris flow

Submarine debris flows were studied through a set of laboratory tests to investigate the flow characteristics and the effects of varying the water content. These tests used the Kaolin clay with water content from 125 to 185% as an artificial marine clay. The observed flow behavior confirmed that submarine debris flows can be divided into strongly coherent flows and weakly coherent flows dependent on the shear strength of sliding material. A deeper understanding of the flow behavior of submarine debris flows has been established through the particle image velocimetry technique. The direction of a strongly coherent flow is parallel to the slope with steady flow velocity. In contrast, the velocity distribution of a weakly coherent flow is in disorder, due to ambient water penetrating the flow head. In this study, a densimetric Froude number Fr-d is presented as the indicator for the threshold of hydroplaning, which occurs if Fr-d is greater than 0.3. In addition, the dimensionless yield stress , is introduced to determine the onset of weakly coherent flow. The threshold value of between strongly and weakly coherent flows is around 0.25.