On the viscous resistance of marine sediments for estimating their strength and flow characteristics

Abstract

To examine debris flow mobility with respect to the runout distance and velocity, strength parameters (e.g., the Bingham and Herschel-Bulkley yield stresses, undrained shear strength, flow behavior index) are needed. In modeling debris flow, the Bingham and Herschel-Bulkley yield stresses are often used, but they lead to large differences in the runout distance and velocity of the failed masses. It is very difficult to determine the true yield stress. In this study, we propose using the viscous resistance, obtained from the normalized flow curve resulting when the shear stress and shear rate are divided by reference shear stress and shear rate values (i.e., \(\log \tau /\tau _0 - \log \gamma /\gamma _0 \)). The viscous resistance and strength parameters are compared from the viewpoint of geotechnology and rheology. The shear strength and flow characteristics of marine sediments can be characterized in terms of the viscous resistance and the viscous resistance is linearly related to other strength parameters (e.g., viscosity, yield stress and undrained shear strength). Thus, the viscous resistance provides a simple and easy approach for approximating strength and flow parameters in debris flow dynamics.