Characterization of undrained shear strength profiles for soft clays at six sites in Texas.

Details

• Alternative Title:
  Project title: Correlation of shallow, low blow count Texas cone penetrometer values and shear strength for Texas soils
• Creators:
  Varathungarajan, David A. ; Garfield, Scott M. ; Wright, Stephen G.
• Corporate Creators:
  University of Texas at Austin. Center for Transportation Research
• Corporate Contributors:
  Texas. Dept. of Transportation. Research and Technology Implementation Office ; United States. Federal Highway Administration
• Subject/TRT Terms:
  • Clay soils
  • Shear strength
  • Soils by permeability
  • Soil penetration test
  • Embankments
  • Clay soils--Texas--Testing
  • Shear strength of soils
  • Embankments--Texas
  • Soil stabilization--Texas
  • Soil penetration test.
• Publication/ Report Number:
  FHWA/TX-09/0-5824-2
• Resource Type:
  Tech Report
• Geographical Coverage:
  Florida
• Edition:
  Technical report; Sept. 1, 2006-Aug. 31, 2008.
• Corporate Publisher:
  University of Texas at Austin. Center for Transportation Research
• Abstract:
  TxDOT frequently uses Texas Cone Penetrometer (TCP) blow counts to estimate undrained shear strength. ; However, the current correlations between TCP resistance and undrained shear strength have been developed primarily for ; significantly stronger soils than are often encountered at shallow depths. Updated existing correlations would allow ; TxDOT to estimate better the undrained shear strength of soft soils for the design of embankments and retaining structures. ; Considering the limited data for these soils, the primary objective of this study was to characterize the undrained shear ; strength profiles for six sites with strengths generally less than 750 psf, such as those commonly found at depths up to ; approximately 30 feet. The undrained shear strength profiles developed in this study were used in further research by ; Garfield (2008) to develop and assess the reliability of new correlations between Texas Cone Penetrometer resistance and ; undrained shear strength of soft clays. ; An analysis was performed comparing strengths measured in unconsolidated-undrained, consolidated-undrained, ; field vane shear, and piezocone penetration tests with respect to strengths from the average strength profiles. The degree of ; sample disturbance in unconsolidated-undrained tests was assessed based on values of axial strain at 75 percent of the ; principal stress difference at failure. While there was significant scatter in the data, unconsolidated-undrained tests gave ; strengths that tended to be significantly lower than strengths from the average profiles. The degree of sample disturbance ; in consolidated-undrained tests was assessed based on the volumetric strain during consolidation to the in-situ effective ; overburden stress. Consolidated-undrained tests on disturbed specimens gave strengths that were approximately 50 percent ; higher than what was believed to be the correct strength. Strengths measured in field vane shear tests were corrected with ; Bjerrum’s (1972) correction factor and found to generally agree well with strengths from the average strength profiles. ; However, vane tests in sandy clays tended to overestimate undrained strengths. Analyses also indicated that piezocone ; penetration tests can be used to establish reasonably accurate undrained shear strength profiles without the need for site ; specific correlations.
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• Format:
  PDF
• Funding:
  0-5824
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/17423/dot_17423_DS1.pdf
• File Type:
  [PDF - 7.73 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:6beec9a346e7d6d0861deecc730f3db8895d45ac980622b6c2090ad52bdd21e4