Abstract: “Mudflow is a type of ground movement that occurs rapidly when the water content of the soil increases, exceeding its liquid limit. The rheological approach is commonly used to study the stress-strain behavior of a mudflow. Two rheological-based parameters used to determine the flow velocity of the mudflow are yield stress and viscosity. In this study, yield stress was assumed to be equal to the undrained shear strength of the cohesive soils. Three laboratory test methods (i.e., the fall cone penetration test, the vane shear test, and the cylinder strength meter) were adopted to estimate the undrained shear strength of kaolin and bentonite soils. The results indicated that the cylinder strength test method had benefits against the other conventional methods in measuring the undrained shear strength of the soils with high water content. The experimental results also show that increasing the water content decreased the undrained shear strength and increased the flow velocity.”

Keywords: mudflow, rheology, yield stress, undrained shear strength