Assessing and Characterizing Geotechnical Soil Strength Parameters for a Systematic Process to Analyze Slope Stability in Accordance With LRFD Methods: Soil Strength Parameters

Details

• Creators:
  Arndt, Ben ; Johnson, Richard
• Corporate Creators:
  Escalante CM and Engineering, Inc. ; RJ Engineering & Consulting, Inc.
• Contributor:
  Lucero, Jeremy
• Corporate Contributors:
  Colorado. Department of Transportation ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  • Stability analysis
  • Cohesion
  • Landslides
  • Clay
  • Embankments
  • Mechanical failure
  • Atterberg limits
  • Testing
  • Load and resistance factor design
  • Slope stability
  More +
• Publication/ Report Number:
  CDOT-2026-10
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Colorado ; Wyoming
• Edition:
  Final Report
• Corporate Publisher:
  Colorado. Department of Transportation
• Description:
  This research report reviews fine grained, clay soil slopes that result in landslides and embankment failures in Colorado and Wyoming. The landslides and embankment distress often require constant roadway maintenance, and full mitigation measures are often beyond roadway funding thresholds. Geotechnical site investigations and resulting slope stability analysis can be problematic with the type of laboratory samples collected and the basis for evaluating the existing stability and proposed mitigation. One method that has been used for the mitigation process of these unstable slopes is modeling of the existing failure condition of the landslide to a factor of safety (FS) of 1.0 known as "back-calculation" or "back analysis" to capture and model the site conditions at the time of slope failure. The report compares Atterberg testing from all the sites and suggests various strength parameters for back-analysis (baseline) stability analysis given the similarity in Cretaceous-age properties. The report reviews the use of both soil strength parameters of ф (friction angle) and c (cohesion) and how these properties relate to direct shear testing and the fundamental importance of using cohesion in back-calculated stability modeling to provide a useful model for comparing various mitigation options. The report also provides examples of back calculation techniques in these Cretaceous-age materials. The research also evaluates and discusses the use of LRFD methods applied and integrated into both slope and structural considerations for a reasonable level of mitigation. Suggestions for incorporating LRFD with slope stability programs and design protocols are discussed.
• Format:
  PDF
• Funding:
  23-HAA-XB-00044
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/93565/dot_93565_DS1.pdf
• File Type:
  [PDF - 11.62 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:90ec27260624a99e5ab0a85bfdf04ef2e35f9440307339dc9904ea97614cc98885937f7899cd839d523c7f28494b95e558ac1c5f9c57b48efa76776ed1748d01