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.
Varathungarajan, David A. ; Garfield, Scott M. ; Wright, Stephen G. Less -
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
Texas. Dept. of Transportation. Research and Technology Implementation Office ; United States. Federal Highway Administration Less -
Subject/TRT Terms:
[+]
Clay Soils--Texas--Testing Embankments--Texas Shear Strength Of Soils Soil Penetration Test. Soil Stabilization--Texas Clay Soils Embankments Shear Strength Soil Penetration Test Soils By Permeability
Publication/ Report Number:
FHWA/TX-09/0-5824-2
Resource Type:
Tech Report
Geographical Coverage:
Florida
OCLC Number:
667706875
Edition:
Technical report; Sept. 1, 2006-Aug. 31, 2008.
Corporate Publisher:
University of Texas at Austin. Center for Transportation Research
NTL Classification:
NTL-HIGHWAY/ROAD TRANSPORTATION-Soils and Geology
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:

Supporting Files

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