Plastic response of circular footings on sand under general planar loading

Abstract

Data from a set of tests of model circular footings on dense sand are presented. The footings were subjected to a variety of combinations of vertical, horizontal and moment loading. The tests were designed to provide the information necessary to construct a complete model of the footing behaviour, based on the concepts of plasticity theory. In particular, the tests provide detailed information about the shape of the yield surface, and so allow generalization of bearing capacity calculations to cases other than purely vertical loading. Information is also obtained about the hardening law and flow rule appropriate for a plasticity model, and the elastic response within the yield surface. Nous présentons ici les données provenant d'un ensemble d'essais sur des modèles d'assises circulaires sur un sable dense. Ces assises ont été soumises à une variété de combinations de charge verticale, horizontale et de moment. Les essais avaient été con&ecil;us pour donner l'information nécessaire à la construction d'un modéle complet du comportement de l'assise, en se basant sur les concepts de la théorie de plasticité. Notamment, les essais donnent une information détaillée sur la forme de la surface d'écoulement, ce qui permet de généraliser les calculs de résistance de portée et de les Réndre à des cas autres que les cas de charge purement verticale. Iis renseignent aussi sur la loi de durcissement et la règle d'écoulement convenant à un modée de plasticitéla réastique àieur de la surface d'écoulement.

An Experimental Study of the Drained Capacity of Suction Caisson Foundations Under Monotonic Loading For Offshore Applications

“…It is clear that the two sets of arrows are very close; indicating that associated ‰ow is applicable for the horizontal and moment plane. This is in agreement with the results from other research on sand, e.g., Gottardi et al (1999), Cassidy (1999) and Byrne and Houlsby (2001).…”

“…As the dilation angle is a non-linear function of the mean eŠective stress level and because the stresses in the laboratory are lower, compared with thê eld, this leads to a higher mobilised peak friction angle in the laboratory test if the same sand density is used as in theˆeld. It should be highlighted that a range of the previously reported data (for instance Gottardi et al, 1999) would indicate that if the results are interpreted within the work hardening plasticity framework the in‰uence of friction angle on the combined load capacity is relatively weak. The loose samples were obtained by carefully placing the sand into the testing tank by keeping the drop height to a minimum.…”

“…3, (ii) a ‰ow rule to describe the incremental plastic displacements at yield, (iii) a description of the elastic behaviour within the yield surface, and (iv) a hardening law to deˆne the expansion or contraction of the yield surface. For further discussion of this framework see Nova and Montrasio (1991), Martin (1994), Cassidy (1999), Gottardi et al (1999), Martin andHoulsby (2000, 2001), Byrne and Houlsby (2001), Houlsby and Cassidy (2002) and Cassidy et al (2002Cassidy et al ( , 2004Cassidy et al ( , 2006. This paper deals with the experimental study of theˆrst three components of the model.…”

“…In particular Byrne (2000) studied very dense sands. A secondary consideration is that Byrne (2000) did not include the tension capacity of caissons in the analysis, assuming a yield surface formulation as proposed by Butterˆeld and Gottardi (1994), Gottardi et al (1999) or Cassidy (1999) for ‰at footings.…”

The Undrained Vertical Bearing Capacity of Skirted Foundations

“…A common design approach (e.g., Zaharescu, 1961;Ticof, 1977) deˆnes a failure envelope in V-H-M load space which is used to size oŠshore foundations under monotonic loading conditions. Combined (V-H-M) loading envelopes are often scaled by the vertical bearing capacity, Vo (e.g., Ticof, 1977; Butterˆeld and Ticof, 1979;Gottardi, 1992;Gottardi et al, 1999) or combinations of the pure vertical (Vo), pure horizontal (Ho) and moment (Mo) capacity (e.g., MurŠ, 1994; Bransby and Randolph, 1998; Gourvenec and Randolph, 2003). Therefore knowledge of the vertical capacity, Vo is imperative for design even for these more complex loading conditions.…”