LONG-TERM STRENGTH OF COMPACTED HIGH-PI CLAYS

Moisture infiltration into earth slopes and structures constructed of high-plasticity clays will lead to a reduction in soil suction and strength that can ultimately result in stability failure. This research presents a rational analysis of this process that: establishes a relationship between soil suction and strength, and provides a framework for predicting the time rate of strength loss due to moisture infiltration into an earth mass. This research utilizes a generalized form of the Mohr-Coulomb failure criterion to characterize the effects of suction on soil strength. A diffusion equation governs changes in soil moisture and suction. This equation is in general non-linear for unsaturated soils; however, this research uses a linearized formulation through appropriate transformation of variables. This research also presents methods for estimating the necessary material parameters needed for input into the moisture diffusion model. The suction-strength relationships and moisture diffusion analyses are applied to back-analyzing a number of shallow slope failures in Texas high-PI (plasticity index) clays. The moisture diffusion analysis is also extended to typical Texas Department of Transportation earth-retaining structures to predict decreases in suction during the life of these structures. Based on these suction predictions, estimates of soil strength within an earth structure as a function of location and time are possible.

• Supplemental Notes:
  • Research Project Title: Long-Term Strength Properties of High-PI Clays Used in Embankment Construction.
• Corporate Authors:

  Texas Transportation Institute

  Texas A&M University System, 1600 E Lamar Boulevard
  Arlington, TX  United States  76011

  Texas Department of Transportation

  Research and Technology Implementation Office, P.O. Box 5080
  Austin, TX  United States  78763-5080

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Aubeny, C
  • Lytton, R
• Publication Date: 2003-2

Language

• English

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: 100 p.

Subject/Index Terms

• TRT Terms: Compacted clays; Earth walls; Embankments; Linear equations; Plasticity index; Slope stability; Soil suction
• Uncontrolled Terms: Mohr-Coulomb failure criterion; Moisture diffusion; Soil strength
• Subject Areas: Geotechnology; Highways; I42: Soil Mechanics;

Filing Info

• Accession Number: 00972252
• Record Type: Publication
• Report/Paper Numbers: FHWA/TX-03/2100-1,, Research Report 2100-1,, TTI: 0-2100
• Contract Numbers: Project No. 0-2100
• Files: TRIS, USDOT, STATEDOT
• Created Date: Apr 30 2004 12:00AM