A hypoplastic theory for granular materials developed by Gudehus and Bauer is discussed. The description of asymptotic states is of particular interest. Three forms of asymptotic states are defined. Useful criteria to describe the tensorial part of the constitutive relation is developed for one of them, namely for the critical states. The terms proposed by Wu are correlated to the well‐known formulations of elastic plastic theory: the Drucker/Prager model and the yield condition by Matsuoka/Nakai. The suitability of the Matsuoka/Nakai criterion for critical states is discussed.
Specification of tensorial functions follows in two steps. First the hypoplastic Drucker/Prager model is developed, and then the limit condition by Matsuoka/Nakai is implemented. The resulting tensorial functions require the critical friction angle as the only material constant. The limit condition in critical states obtained from the hypoplastic law coincide with the one by Matsuoka/Nakai. A more comprehensive hypoplastic constitutive relation based on these new tensorial functions is discussed and applied to simulations of element tests. These numerical results are compared with experimental results for sand.
SUMMARYA new version of a hypoplastic constitutive equation is presented which is characterized by the introduction of a stress-like internal parameter called back stress. The back stress is a function of the void ratio and of the hydrostatic stress. Using a unique set of material constants, the new constitutive equation describes many aspects of the behaviour of cohesionless soils including the influence of density and stress level. This is demonstrated by a series of verification tests. The determination of the material constants from laboratory tests is described analytically.
Die Schleuse Uelzen I ist wegen ihrer flexiblen Tragstruktur, den großen Lastwechsel während des Schleusenbetriebs und der 1992 installierten, umfangreichen meßtechnischen Überwachung ein sehr gut geeignetes Anwendungsbeispiel, um das Interaktionsverfahren zwischen Bauwerk und Boden unter zyklischen Beanspruchungen zu untersuchen. Es werden dreidimensionale Finite‐Elemente‐Berechnungen durchgeführt, um das Langzeit‐Verhalten der Schleuse bei zyklischen Beanspruchungen zu prognostizieren. Entscheidend dafür ist, daß das Stoffmodell für den Boden auch das quasistatische zyklische Verhalten realitätsnah erfaßt. Das verwendete hypoplastische Stoffmodell mit intergranularer Dehnung wird kurz beschrieben. Die Ergebnisse der numerischen Berechnungen werden mit gemessenen Setzungen der Schleuse verglichen. Es werden zum Vergleich die Ergebnisse von hypoplastischen Berechnungen ohne intergranulare Dehnung und von elastisch‐idealplastischen Berechnungen mit dem Mohr‐Coulobschen‐Modell vorgestellt. Siloeffekte im Hinterfüllungsbereich zwischen den Rippen der Schleuse verringern sich infolge der zyklischen Beanspruchungen in Verbindung mit "stick‐slip"‐Verhalten.
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