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 Clay Soils--Texas--Testing Embankments Embankments--Texas Shear Strength Shear Strength Of Soils Soil Penetration Test Soil Penetration Test. Soils By Permeability Soil Stabilization--Texas
• 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.
  
  
• Format:
  PDF
• Funding:
  0-5824
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:6beec9a346e7d6d0861deecc730f3db8895d45ac980622b6c2090ad52bdd21e4
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/17423/dot_17423_DS1.pdf
• File Type:
  [PDF - 7.73 MB ]