CREEP OF COMPACTED CLAYS

THE OVERALL AIM IS TO OBTAIN A DEPENDABLE MEANS FOR PREDICTING THE LONG-TERM DEFORMATION OF COMPACTED CLAY EMBANKMENTS. THIS PHASE OF THE WORK IS CONCERNED WITH A USEFUL DESCRIPTION OF THE TIME-DEPENDENT STRESSS- STRAIN BEHAVIOR OF CMPACTED COHESIVE SOILS. LABORATORY TESTS, INCLUDING A MODEL STRIP LOADING TEST, ON "EDGAR PLASTIC KAOLIN" AND ON "GRUNDITE" INDICATE THE FOLLOWING: (1) WHEN A COMPACTED CLAY IS SUBJECTED TO A SERIES OF LOAD AND UNLOAD CYCLES OF GIVEN STRESS LEVEL, THE DIFFERENCE IN RESPONSE BETWEEN THE SECOND AND SUBSEQUENT CYCLES IS MUCH LESS THAN BETWEEN THE FIRST AND SECOND CYCLES. FOR SECOND AND SUBSEQUENT LOADINGS, THE MECHANICAL BEHAVIOR OF COMPACTED CLAY CAN BE DESCRIBED BY A NON-LINEAR VISCOELASTIC CONSTITUTIVE RELATION BASED UPON THE PRINCIPLES OF IRREVERSIBLE THERMODYNAMICS. (A) NON-LINEAR EFFECTS CAN BE ACCOUNTED FOR BY TIME-INDEPENDENT PARAMETERS WHICH ARE FUNCTIONS OF THE STRESS-STRENGTH RATIO, I. E., THE RATIO BETWEEN THE OCTAHEDRAL SHEAR STRESS AT FAILURE CORRESPONDING TO THE EXISTING OCTAHEDRAL NORMAL STRESS. (B) A POWER-LAW REPRESENTATION IS VALID TO REPRESENT TIME-DEPENDENT EFFECTS. (C) THE EFFECTS OF MOISTURE CONTENT AND CONFINEMENT ARE APPROXIMATELY ACCOUNTED FOR BY THIS CONSTITUTIVE LAW. (D) THE VALIDITY OF THE CONSTITUTIVE RELATION IS INDEPENDENT OF THE SCALE OF PROBLEM CONSIDERED PROVIDED THE COMPACTION CONDITIONS ARE SUCH THAT THE EFFECITVE STRESSES APPROXIMATE THE APPLIED TOTAL STRESSES. (2) THE APPLICABILITY OF THE CONSTITUTIVE RELATION, DETERMINED FROM TRIAXIAL TESTS, WAS EXAMINED BY PREDICTING THE DISPLACEMENTS (ON SECOND LOADING) OF A MODEL FOOTING LOADED UNDER PLANE STRAIN CONDITIONS. THE AGREEMENT WITH EXPERIMENTAL RESULTS WAS EXCEPTIONALLY GOOD. LABORATORY COMPACTED CLAYS EXHIBIT ANISOTROPIC MECHANICAL BEHAVIOR. THE IMPORTANCE OF THIS ANISOTROPY TO THE PREDICTION OF THE BEHAVIOR OF COMPACTED EMBANKMENTS REMAINS TO BE ASSESSED. /FHWA/

• Corporate Authors:

  Indiana State Highway Commission

  Indianapolis, IN  United States  46204

  Federal Highway Administration

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

  Purdue University

  School of Aeronautics and Astronautics
  West Lafayette, IN  United States  47907
• Authors:
  • Ramaswamy, R S
• Publication Date: 1971-7

Media Info

• Features: Appendices; Figures; Tables;
• Pagination: 205 p.

Subject/Index Terms

• TRT Terms: Clay; Cohesive soils; Compaction; Creep; Deformation curve; Embankments
• Subject Areas: Geotechnology; Highways;

Filing Info

• Accession Number: 00233744
• Record Type: Publication
• Source Agency: Federal Highway Administration
• Report/Paper Numbers: No. 12
• Files: TRIS, USDOT
• Created Date: Feb 15 1972 12:00AM