Evaluation of an Equivalent Mean Grain Size Diameter to Rationally Predict the Erodibility of Fine Riverbed Soils in Nebraska

Authors

Basil Abualshar, University of Nebraska-LincolnFollow

First Advisor

Chung Song

Date of this Version

6-2022

Citation

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.

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Civil Engineering, Under the Supervision of Professor Chung R. Song. Lincoln, Nebraska: June, 2022

Copyright © 2022 Basil Abualshar

Abstract

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