Barodesy for clay

Abstract

Barodesy is a new hypoplastic frame for constitutive models to describe granular materials. It has already been introduced for sand, and this article adjusts barodesy for clay. Common concepts of soil mechanics, such as critical states, barotropy (i.e. the dependence of stiffness and strength on the stress level), pyknotropy (i.e. the dependence of stiffness and strength on density) and a stressdilatancy relation can easily be included in the presented model. Despite its mathematical simplicity, barodesy is able to describe many aspects of clay behaviour. Only four material constants are required, which can be determined by means of a single consolidated undrained triaxial test.

An improved version of barodesy for clay

“…However, an article [21] reviews existing experimental evidence on stress-dilatancy relations and discusses it in the framework of barodesy, but does not provide a constitutive model. The main differences of barodesy for clay [20] and the version presented here are shown in this article. The tensor R and the scalar quantities f and g have been changed, and the calibration procedure is simplified as compared to [20].…”

“…The main differences of barodesy for clay [20] and the version presented here are shown in this article. The tensor R and the scalar quantities f and g have been changed, and the calibration procedure is simplified as compared to [20].…”

“…1 In a, b, w _ e and w r according to [8] are defined in the Rendulic plane: i refers to isotropic compression; o to oedometric compression; c to isochoric triaxial compression; and Àc to isochoric triaxial extension. In c, barodesy for clay [20] (2012) is compared with the version presented here (2016), and u c is chosen as 22:6 2 The term objectivity points to the fact that material behaviour is frame-indifferent, i.e., the behaviour is independent of the observers' motion. 3 In general, stretching D is only approximately equivalent to the strain rate _ e. For rectilinear extensions, D equals _ e, with _ e being the logarithmic strain tensor.…”

“…In 2012, Medicus et al [20] modified the sand version [10] and introduced barodesy for clay. A major component of barodesy is the so-called R-function, which links proportional strain paths to proportional stress paths and thus acts as a stress-dilatancy relation.…”

“…A major component of barodesy is the so-called R-function, which links proportional strain paths to proportional stress paths and thus acts as a stress-dilatancy relation. Former versions of R in barodesy [4,[9][10][11][12]20] allow proportional stress paths to reach the tensile area. Experiments by Bergholz [1] of saturated reconstituted clay show that, also for highly overconsolidated clay, the stress ratio q/p (in triaxial compression) does not exceed three (i.e., the stress paths stay in the compression regime).…”