Relationship between Erodibility and Fundamental Geotechnical Properties of Geomaterials

Knowledge of the erodibility of geomaterials is essential to the analysis of problems related to soil erosion which include bridge scour, embankment overtopping erosion, and stream stability. Erodibility directly influences the scour and erosion potential of geomaterials under hydraulic loads. This is a primary source of concern for highway bridges where scour has been the leading cause of bridge failures in the United States, contributing to approximately 60% of failures since 1970. A geomaterial's resistance to erosion is dependent on several mechanisms, including the material structure and the inter-particle forces that develop. Erodibility is generally defined as the relationship between the erosion rate and the shear stress imposed by flowing water at the soil/‌rock-water interface. Another key element that describes erodibility is the erosion threshold parameter. This parameter, termed the critical shear stress, is defined as the hydraulic shear stress corresponding to an erosion rate that, for all practical purposes, is negligible. Erosion is considered not to occur below this threshold. While there are specialized devices available to measure erodibility, their use can be expensive due to the following: (1) requirement of site-specific material sampling; (2) the need of specialized and experienced test operators; and (3) potential high cost of the testing equipment. In an attempt to overcome the high costs associated with erosion testing, researchers in the past have attempted to develop relationships between geotechnical properties of geomaterials and erodibility. Some of the geotechnical properties that have been studied include unit weight, plasticity index, shear strength, void ratio, fines content, water-chemical composition, and sodium absorption ratio. These investigations did not yield meaningful results possibly due to: (1) lack of emphasis on the influence of material structure on erodibility; (2) use of datasets from multiple sources where test conditions and procedures may have varied significantly; (3) inadequate number of datasets that contain both information on erodibility and geotechnical properties to meaningfully investigate their relationship, for example by using statistical regression techniques; and (4) inappropriate application or lack of knowledge of available statistical methods that are best suited to analyze the data. All these factors have led to very limited guidance available on the relationship between erodibility and geotechnical properties. The objective of this research is to determine relationships between erodibility and fundamental geotechnical properties that can be used as cost effective means to assess site‑specific erosion resistance of geomaterials. Accomplishing this objective will require the following tasks: (1) Perform a literature review on the past research conducted in this area. (2) Conduct a survey of state department of transportation DOT practices on typical geotechnical properties measured in the laboratory and in-situ, and also specifically how erodibility is quantified. (3) Perform a survey on the available methods of laboratory erosion testing. (4) Select geomaterial types and the fundamental geotechnical properties that are to be included in the study. (5) Select erosion testing procedure that is to be adopted for the study. (6) Perform erosion tests using the selected laboratory erosion testing procedure to measure the erodibility of geomaterial samples. (7) Perform laboratory and/or in-situ tests to obtain the fundamental geotechnical properties of the geomaterials such that each geomaterial sample has both erodibility and geotechnical properties. (8) Perform a survey on available statistical techniques applicable to the data. (9) Develop correlations and relationships between erodibility and geotechnical properties using sound statistical techniques. (10) Present results in a simple and meaningful manner that can be readily used by the engineering practitioner.


  • English


  • Status: Proposed
  • Contract Numbers:

    Project 24-43

  • Sponsor Organizations:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway & Transportation Officials

    444 North Capitol Street, NW, Suite 225
    Washington, DC  United States  20001

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    Reynaud, David

  • Start Date: 20141116
  • Expected Completion Date: 0
  • Actual Completion Date: 0
  • Source Data: RiP Project 37533

Subject/Index Terms

Filing Info

  • Accession Number: 01543524
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 24-43
  • Files: TRB, RiP
  • Created Date: Nov 17 2014 1:01AM