Date of this Version
Basil Abualshar. (2022). "Evaluation of an Equivalent Mean Grain Size Diameter to Rationally Predict the Erodibility of Fine Riverbed Soils in Nebraska", MS thesis, Civil and Environmental Engineering Department, University of Nebraska-Lincoln, Lincoln, NE, 68588.
The erosion of riverbed soils under the bridges is one of the major reasons that cause bridge closure or failure leading to a significant effect on the local economy. One of the commonly used methods to predict the erosion rate of soils is the excess shear stress method, which is based on two parameters describing the erodibility behavior; the erodibility coefficient and the critical shear stress. On the other hand, studies showed that the mean grain size diameter D50 could be correlated to the erosion resistance of soils, usually for cohesionless soils but not for cohesive soils. It is because the cohesive soils are small and typically plate or needle shape, and erosion may be affected by several intergranular forces which are not prominent in cohesionless soils. Therefore, if D50 technique revised to be used for cohesive soils, the prediction of riverbed erosion may become much convenient.
This study aimed to find the equivalent sand particle diameter experimentally for fine-grained soils in Nebraska around Lincoln so that the erosion of these soils can be predicted conveniently. To achieve this goal, 17 soil samples from different rivers around Lincoln in Nebraska were tested using the Mini Jet Erosion Testing device to obtain the erodibility coefficient and the critical shear stress. Then, the results were analyzed to conveniently obtain the equivalent D50 of the sand for the same critical shear stress graphically. With this procedure, engineers may conveniently analyze the erosion of riverbed fine-grained soils based on popular software which utilize D50.
Advisor: Chung R. Song