SOIL SHEAR STRENGTH

THE VANE DEVICE OFFERS A SIMPLE MEANS FOR TAKING SHEAR STRENGTH MEASUREMENTS OF WEAK OR SENSITIVE CLAYEY SOILS. SO THE ENGINEER COULD BETTER DETERMINE HOW TO INTERPRET THE TEST DATA, THIS STUDY WAS UNDERTAKEN TO CLARIFY THE INFLUENCE OF TESTING VARIABLES AND OF IN-SITU STRESS AND STRAIN CONDITIONS ON VANE SHEAR STRENGTH DATA. THE DATA CLEARLY SHOWED THAT THE MEASURED SHEAR STRENGTH OF A CLAY SOIL IS DEPENDENT ON THE TEST SPEED. THIS DEPENDENCE IS PROBABLY A FUNCTION OF TWO INDEPENDENT VARIABLES -- EFFECTIVE STRESSES AND SHEAR STRENGTH PROPERTIES OF THE SOIL THE VANE SHEAR STRENGTHS OF CLAY SOILS TENDED TOBE GREATER THAN THE UNCONFINED COMPRESSION SHEAR STRENGTHS, WITH THE RATIO OF THE UNCONFINED VANE TO UNCONFINED COMPRESSION SHEAR STRENGTHS VARYING FROM 0.8 TO 1.4. THE DIFFERENCES IN THE TWO TYPES OF STRENGTHS ARE QUITE SMALL WHEN VIEWED IN TERMS OF THE LARGE INFLUENCE OF SAMPLING DISTURBANCE ON THE SHEAR STRENGTH OF SOFT CLAY SOILS. AS A MEANS TO INVESTIGATE THE IN-SITU SHEAR STRENGTH, ARTIFICALLY SLURRIED SOILS WERE CONSOLIDATED AND TESTED IN A CONSOLIDOMETER TYPE OF DEVICE, AND REFERRED TO AS TRIAXIAL VANE TESTS. TRIAXIAL VANE SHEAR STRENGTHS WERE TAKEN FOR A RANGE OF CONSOLIDATION STRESSES OF NORMAL INTEREST IN FIELD TESTING. THE TRIAXIAL VANE SHEAR STRENGTH ENVELOPE OF A HIGHLY PLASTIC CLAY WAS SIMILAR IN SHAPE TO A TYPICAL TRIAXIAL COMPRESSION SHEAR STRENGTH ENVELOPE, BUT THE VANE SHEAR STRENGTH ENVELOPES FOR A LOW AND A MEDIUM PLASTICITY SOIL APPEARED TO DIFFER CONSIDERABLY FROM TYPICAL TRIAXIAL COMPRESSION SHEAR STRENGTH ENVELOPES. A POSSIBLE FIELD USE FOR THE LABORATORY TYPE OF VANE APPARATUS IS SET FORTH.

• Supplemental Notes:
  • RPT NO FHWA-RD-73-47
• Authors:
  • Obermeier, S F
• Publication Date: 0

Media Info

• Pagination: 37 p.

Subject/Index Terms

• TRT Terms: Clay soils; Deformation curve; Shear strength; Soil tests; Triaxial shear tests; Vane shear tests
• Subject Areas: Geotechnology; Highways;

Filing Info

• Accession Number: 00228696
• Record Type: Publication
• Source Agency: Federal Highway Administration
• Files: TRIS, USDOT
• Created Date: May 7 1974 12:00AM