Strain-rate dependency of strength of soft marine deposits of the Gulf of Mexico

Many marine civil engineering applications require knowledge and understanding of the behavior and strength properties of soft cohesive marine sediments under high strain-rate conditions, typically encountered during impact penetration events of sediment probes and other objects as a result of free fall through the water column. In order to investigate these effects, a series of variable rotational rate vane shear tests were performed using a precision rheometer and spanning the rotational rate range of 0.25 to 1000 [1/min]. A wide range of water contents from 65 to 95% was examined as a primary influence on the response of a particular saturated silty clay material. Non-linearities in the behavior of the soft mud were analyzed and applicability and precision of various models examined. A modified rate equation is suggested yielding good correlation with experimental data at all water contents and all rotational rates explored.