Abstract: Submarine mud flow is a kind of dilute submarine landslide body which is evolved by complex soil and water exchange after the unstable sliding of submarine slope. It shows the dual characteristics of soil and fluid. However, it is difficult to obtain the continuous changing strength under low shear strain rate by the existing testing methods, and the comprehensive strength characteristics can not be well revealed. The rheological and strength properties of the simulated submarine mud flow at different shear strain rates are investigated by using new full-flow penetrometer and RST rheometer, and the relevance of the undrained shear strength, yield stress and apparent viscosity with moisture content are analyzed according to the experimental results. Based on the shear thinning theory, a piecewise fitting model is developed to describe the rheological relation of submarine mud flow from low to high shear strain rate. Then, the new rheological model shows a good applicability and advantages through the comparison with other conventional models. In addition, an undrained shear strength model of submarine mud flow is established by considering the effect of strength softening, which provides a scientific basis for the numerical simulation and disaster assessment of submarine mud flow movement.

Key words: submarine mud flow, rheology test, strength model, undrained shear strength, submarine landslide