A small‐strain overlay model

Abstract

SUMMARYThe paper begins with a discussion of the phenomenon of small-strain stiffness and presents the smallstrain overlay model, a simple model that takes into account the non-linear stiffness of soils at small strains. The new model can enhance already established elastoplastic formulations for non-linear stiffness variation at small strains in a similar way that intergranular strain enhances the hypoplastic model. The overlay model is driven by the material's strain history and only two additional material constants, both with clear physical meaning. Therefore, the proposed model is a step towards the incorporation of smallstrain stiffness into routine design. In this paper, the new small-strain overlay model is formulated. Its ability to take into account the influence of various strain histories on soil stiffness is illustrated in several examples.

Isolated soil mass at foundation for mitigating seismic risk

“…Hence, to model a realistic behaviour of the ground, allowing for stress and strain dependence of stiffness and capturing the hysteretic behaviour of sand and the associated hysteretic damping in unloading-reloading cycles, Hardening Soil with small-strain overlay was used (Benz et al, 2009;Schanz et al, 1999). This is a constitutive model implemented in the Plaxis code that takes into proper account strain hardening plasticity and small-strain behaviour of sand.…”

Numerische Simulation im Tunnelbau

“…Für monotone Belastungen repräsentiert g die Norm der Schubverzerrungen, g 0,7 ist der Wert von g, bei dem die Schubsteifigkeit auf 70 % des Initialwerts gesunken ist [18,69] …”

“…Dies erfordert eine geeignete Strategie zur Berücksichtigung der Verzerrungsgeschichte, über die g in Gl (33). in diesem Fall als pfadabhängige Variable g hist eingeht[18].Die Berücksichtigung einer erhöhten Steifgkeit bei kleinen Verzerrungen (small strain stiffness) verbessert die Ergebnisse der Simulation im Hinblick auf die Form der Setzungsmulde (Bild 27)[181]. Die Verwendung von Mohr-Coulomb-(MC)-und Hardening-Soil-(HC)-Modellen resultiert i. Allg.…”

A multilaminate constitutive model accounting for anisotropic small strain stiffness

“…Different approaches have been followed in constitutive modelling in order to capture this effect. Whereas kinematic hardening models monitor load history in stress space , defining load history in strain space has been preferred in small strain stiffness models . While each approach has its merits, monitoring load history in terms of strains is more consistent with stiffness degradation, which is also driven by strains rather than stresses.…”