LINEARIZING TRIAXIAL TEST FAILURE ENVELOPES

Soil variability biases both the best-fit-by-eye and linear regression of p-q triaxial test data plots (where p represents the abscissa of the center of a Mohr circle and q is the radius) to substantially overestimate the friction angle phi. This is because linear regression of q on p assumes that variability lies in the y-axis direction, whereas if lateral stress sigma sub 3' is constant, variability is 45 deg to the y-axis. A correct regression is quickly performed by converting p-q data points to polar coordinates, adding 45 deg or another angle indicated by the mean stress paths to the coordinate angle, converting back to rectangular coordinates and performing the linear regression. The correlation coefficient thus obtained is lowered because it correctly assesses data variability. Without correction the error in phi may be as much as 10 deg. (Author)

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/01496115
• Corporate Authors:

  American Society for Testing and Materials (ASTM)

  100 Barr Harbor Drive, P.O. Box C700
  West Conshohocken, PA  United States  19428-2957
• Authors:
  • Handy, R L
• Publication Date: 1981-12

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 188-191
• Serial:
  • Geotechnical Testing Journal
  • Volume: 4
  • Issue Number: 4
  • Publisher: ASTM International
  • ISSN: 0149-6115
  • EISSN: 1945-7545
  • Serial URL: https://www.astm.org/products-services/standards-and-publications/geotechnical-testing-journal.html

Subject/Index Terms

• TRT Terms: Coefficients; Correlation analysis; Friction; Linear regression analysis; Soil tests; Triaxial shear tests; Variables
• Uncontrolled Terms: Friction angle
• Subject Areas: Data and Information Technology; Geotechnology; Highways;

Filing Info

• Accession Number: 00362344
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 30 1982 12:00AM