Modified triaxial apparatus for nonuniform loading beyond frictional ends

Randa Asmar, Youssef M A Hashash

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Available laboratory testing devices are designed to generate uniform stress and strain states within a tested specimen. Accordingly, these devices provide information on material behavior within a narrow range of stress-strain paths and do not cover the loading conditions that occur in field problems. This limited information generally results in a constitutive model that may not be justifiable to represent loading conditions that differ substantially from the ones in laboratory tests. This paper presents the design of a newly developed next generation laboratory testing device that imposes nonuniform loading on a soil specimen beyond frictional ends. This device is integrated with an evolutionary inverse analysis computational engine to develop a soil constitutive model that reliably captures the soil behavior under general loading conditions. The design inherits features of the conventional triaxial test and adds frictional ends and lateral displacement restraint clamps. Numerical simulation showed that the sheared specimen with clamps includes shear modes that cannot currently be mobilized with available testing devices. The employed close-range digital photogrammetry system measures 3D lateral deformations at 0.5% axial strain or greater with a maximum error of about 2.5%.

Original languageEnglish (US)
Title of host publicationGeo-Congress 2014 Technical Papers
Subtitle of host publicationGeo-Characterization and Modeling for Sustainability - Proceedings of the 2014 Congress
PublisherAmerican Society of Civil Engineers (ASCE)
Number of pages10
Edition234 GSP
ISBN (Print)9780784413272
StatePublished - 2014
Event2014 Congress on Geo-Characterization and Modeling for Sustainability, Geo-Congress 2014 - Atlanta, GA, United States
Duration: Feb 23 2014Feb 26 2014


Other2014 Congress on Geo-Characterization and Modeling for Sustainability, Geo-Congress 2014
Country/TerritoryUnited States
CityAtlanta, GA

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Civil and Structural Engineering
  • Building and Construction
  • Architecture


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