Journal Published Online: 04 June 2018
Volume 41, Issue 5

Effective Stress Strength Parameters of Clays from DMT



In this study, an established effective stress limit plasticity solution for piezocone penetration tests (CPTu) in clay developed by the Norwegian Institute of Technology (NTH) for evaluating the effective stress friction angle (ϕ′) is extended to flat plate dilatometer tests (DMT) readings. A nexus between CPTu and DMT is built through spherical cavity expansion solutions for undrained penetration to link the cone tip resistance (qt) and shoulder porewater pressure (u2) from CPTu to the measured contact pressure (p0) and expansion pressure (p1) obtained from DMT in soft to firm intact clays. Data from 49 paired sets of CPTu-DMT soundings in a variety of clays are used to support and validate the links. A variety of soils ranging from lean to plastic clays and clayey silts from marine, alluvial, lacustrine, deltaic, and glaciofluvial origins are subjected to flat DMTs, and the measurements are utilized to evaluate the effective stress friction angle (ϕ′). Data from 46 clays are compiled to examine the DMT-interpreted ϕ′ values in comparison with laboratory benchmark ϕ′ values obtained from CAUC or isotropically consolidated undrained triaxial compression tests on high-quality samples. An approximate inversion of the theoretical solution is derived to allow ϕ′ profiles to be determined with depth. Four well-documented DMT examples, including two natural clay sites and two chamber test series (one pressurized and the other unpressurized), are presented to illustrate the NTH procedures.

Author Information

Ouyang, Zhongkun
School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA
Mayne, Paul W.
School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA
Pages: 17
Price: $25.00
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Stock #: GTJ20170379
ISSN: 0149-6115
DOI: 10.1520/GTJ20170379