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Geotechnical & Foundation Design

Improved Calculation of Scour Potential in Cohesive Soils and Scour Susceptible Rock

Project Number: SPR-1688

Contract Number: 2016-0067

Status: Complete

Start Date: 05/01/2017

End Date 12/31/2020


This report summarizes the work on the improved calculation of scour potential in cohesive soils and scour-susceptible rock. A state of the practice survey was first conducted to gather information about the scour evaluation in cohesive soils and scour-susceptible rock. This includes a literature review covering the concepts and understanding of scour susceptibility, material sampling, and erodibility testing techniques, bridge scour calculation methods and other factors that can affect the scour analysis in cohesive soils and scour-susceptible rock, and a summary of the information gathered in communications with engineers from MDOT and other state DOTs. Based on the survey, three scour analysis methods, i.e., SRICOS-EFA, EIM, and GSN were selected. Detailed theories, implementation, needed input, and expected output as well as relevant testing were investigated to prepare the knowledge and guidelines that MDOT engineers will need for using these methods. Case studies of two clay-bedded bridge sites and two rock-bedded bridge sites were performed with typical information such as plans and geotechnical reports. Based on the survey, theoretical analysis, and case studies, detailed guidelines for applying the methods, including sampling, testing, and calculation, were presented in the form of flowcharts. Next, the surface geology of Michigan was discussed to help engineers gain a general understanding of the rock in Michigan for bridge scour considerations, and a rock classification was provided to assist more specific assessments. Typical issues for the application of the selected methods, i.e., at sites without stream gages and sites with layered earth strata, were discussed together with their solutions.





Research Manager Project Manager Performing Organization
 Staff photo of Michael Townley  Project Manager Rebecca Curtis  Michigan Technological University logo
 Michael Townley  Rebecca Curtis  Michigan Technological University