Suitability of a Linear Model for Predicting Cohesive Soil Detachment during Jet Erosion Tests

Cohesive soil detachment is a complex process that is typically simulated using simplified mathematical models such as the linear excess shear stress equation or power laws. The assumption of linearity between applied shear stresses and erosion rates has repeatedly been questioned, and several nonlinear models have been proposed as alternatives; however, recent studies demonstrated that over the limited range of tested shear stresses, nonlinear models did not describe erosion data significantly better than linear models did. Questions remain regarding the linearity of this relationship at higher ranges of applied shear stress. Laboratory mini jet erosion tests (JETs) were conducted on remolded samples of cohesive soils. A series of statistical tests were then performed to evaluate the suitability of a linear model for describing the relationship between applied shear stress and JET-derived erosion data. For most of the trials, the statistical analysis rejected the assumption of linearity between the erosion rate and applied shear stress. For certain trials, however, it was not possible to conclude on the nonlinearity of the erosion mechanism due to the limited number of erosion data points or the narrowness of the applied shear stress range. Additionally, even though the linear model could provide a good approximation of the erosion data derived using a standard in situ JET procedure typically limited to a narrow shear stress range, its extrapolation potential for prediction of erosion outside of the tested range is limited.