Asymptotic state boundaries and peak states in barodesy for clay

Abstract

With constant stretching of soil, the memory is gradually swept out and the so-called asymptotic states are reached: asymptotic states are proportional stress paths as well as particular curves in the void ratio against the mean stress plane. The so-called asymptotic state boundary surface (ASBS) serves as a graphical representation for asymptotic states. In contrast to asymptotic states, peak states of drained triaxial tests are states with vanishing stiffness. In this paper, an explicit formulation of the ASBS and peak state envelope of barodesy are introduced. Different clay types are compared with barodesy as well as with predictions by hypoplasticity. The peak states of the experiments confirm the results obtained with barodesy and hypoplasticity. It is shown that different to elastoplastic models, the ASBS does not include peak states in barodesy and hypoplasticity. In addition to standard axisymmetric simulations, investigations are also carried out in the deviatoric plane with the focus on plane strain failure.

Reloading in barodesy employing the asymptotic state boundary surface

“…For highly overconsolidated soils, the model is able to predict peak states with mobilized friction angles . Possible states, that can be reached by proportional stretching are defined by the so‐called asymptotic state boundary surface (ASBS) 11 . The barodetic framework, in its basic version, is well suited to predict loading and unloading and to describe the asymptotic behaviour of the soils.…”

“…In this article, we propose an extension to overcome these ratcheting effects and to improve the predicted reloading behaviour within an intermediate strain range. Therefore the distance of the actual state to the asymptotic state boundary surface (ASBS) 11 is used. This measure is combined with a stiffness‐dilatancy relation that allows for a specific stiffness increase of the reloading behaviour.…”

Erweiterte Anwendung der Barodesie für Finite‐Elemente‐Berechnungen

“…Werden die möglichen Spannungszustände im asymptotischen Zustand mit p e normiert, folgt die Form der ASBS [25, 34], die in Bild 3 für axialsymmetrische Zustände dargestellt ist. Die ASBS dient als grafische Darstellung für asymptotische Zustände.…”

“…Dies wird durch die Kombination des Konzepts der ID mit der sog. asymptotischen State Boundary Surface (ASBS) der Barodesie [25] erreicht.…”

“…Ein Verfahren zur Parameterreduktion bei der Barodesie wurde von [28] eingeführt. In diesem Aufsatz wird ein erweiterter Ansatz vorgestellt, der unter Berücksichtigung der ASBS der Barodesie [25] eine robustere Berechnung und damit eine bessere Interpretation der Ergebnisse ermöglicht. Ein ähnliches Verfahren wurde zeitgleich für die Hypoplastizität von [29] entwickelt.…”