Geotechnical and Geological Engineering
MODELLING THE RESPONSE OF SHALLOW FOUNDATIONS UNDER GENERAL LOADING
RESEARCH GROUP: Guido Gottardi, Laura Govoni, Michela Marchi
KEYWORDS: soil-structure interaction, macroelement, stability of equilibrium, off-shore foundations, towers
The response of shallow foundations subjected to combined loading has been intensively investigat- ed for the last two decades. The understanding of their behaviour is crucial in many structural and geotechnical applications, not only off-shore like wind turbines, but also for other structures like gravity walls, chimneys, historical towers (Fig. 1). Among the most innovative and advanced analy- sis methods, the so-called Macro-element models enable to apply the external resultant forces (V, M/B, H) and displacements (w, θB, u) to the whole foundation and surrounding soil system, as generalised stress and strain variables (Fig. 2). This conceptual framework is simpler and more intuitive than the well-known finite element methods and, at the same time, it is more rational and consistent with the cultural background of the civil engineer.
The research group has worked for many years on these topics, moving from extensive experimen- tal campaigns involving several 1g and centrifuge tests carried out on shallow and embedded foot- ings. These data have been interpreted through simple elastic, hardening-plastic models which are able to reproduce a footing response to gener- al loading conditions with success. These models have been also modified to accommodate other important phenomena such as the soil creep and have been used to explore the stability of histor- ical towers, whose soil-structure interaction is strongly time dependent. More recently the re- search group is exploring the use of more sophis- ticated constitutive models which can be model the footing response to other loading condition, such as cyclic or dynamic. The research group is currently planning further experimental tests to develop such models.
The research has been carried out in collaboration with the University of Southampton, the Oxford University, The Centre for Offshore Foundation Systemsof Perth (WA), the Politecnico of Torino.
Geotechnical and Geological Engineering – Foundations
Fig. 1. Two examples of structures with shallow foundations under combined loading: wind turbine and historical towers (in the picture a scheme of a wind turbine and the ‘Two Towers’ in Bologna).
Fig. 2. Yield surface of a surface footing on sand in the 3D space of applied loading components.
MAIN PUBLICATIONS
Marchi M., Fabbi I., Gottardi G., Butterfield R., Lancellotta R. (2013). Analytical model- ling of the creep-rotation rate for leaning tow- ers. 2nd TC301 Int. Symp. on Geotech. Eng. for the Preservation of Monuments and Historic Sites, 30-31 May 2013, Napoli, Italy. ISBN: 9781138000551.
Marchi M. (2012). Effect of creep on the stability of leaning towers. 22nd European Young Geotech- nical Engineers Conference. Gothenburg, Sweden, 26-29 August, 2012. ISBN: 978-91-637-1435-1. Govoni L., Gourvenec S., Gottardi G. (2011). A centrifuge study on the effect of embedment on the drained response of shallow foundations under combined loading, Géotechnique, Vol. 61(12), 1055-1068. ISSN: 0016-8505.
Marchi M., Butterfield R., Gottardi G. Lancel- lotta, R. (2011). Stability and strength analysis of leaning towers. Géotechnique, Vol. 61(12), 1069-1079, ISSN: 0016-8505.
Govoni L., Gourvenec S., Gottardi G. (2010). Centrifuge modelling of circular shallow foun- dations on sand, International Journal of Physi- cal Modelling in Geotechnics, Vol. 10(2), 35-46. ISSN: 1346-213X.
Gourvenec S., Govoni L., Gottardi G. (2008). The effect of embedment on the response of shallow foundations on sand under general loading, BGA International Conference on Foun- dations, Dundee, Scotland, 24-27 June 2008. 873-884. ISBN: 978-1-84806-044-9.
Gottardi G., Cavallari L., Marchi M. (2008). Soil fracturing of soft silty clays for the rein- forcement of a bell tower foundation. Geotech- nics of Soft Soils. University of Strathclyde, Glas- gow, Scotland, 3-5 Sept. 2008. Vol. 1, 31 - 41, ISBN: 978-0-415-47591-4
Marchi M., Gottardi G., Butterfield R., Zervos A. (2008). On the stability of Santo Stefano bell tower in Venice. 2nd BGA International Confer- ence on Foundations, ICOF 2008. Dundee, Scot- land, UK, 24-27 June 2008. Vol. 2, 1581-1592, ISBN: 978-1-84806-044-9
Gottardi G. (2007). Recenti sviluppi nella mod-
ellazione del comportamento di fondazioni su- perficiali. Relazione Generale, V Convegno Na- zionale dei Ricercatori di Ingegneria Geotecnica su “Fondazioni Superficiali e Profonde”, Politecnico di Bari, 15-16 Sept. 2006; Vol. 2, 85-119. Govoni L., Gourvenec S., Gottardi G., Cassidy M.J. (2006). Drum centrifuge tests of surface and embedded footings on sand, International Conference on Physical Modelling in Geotechnics, Hong Kong, China, 4-6 August 2006, 651-657. Gottardi G., Govoni L., Butterfield R. (2005). Yield loci for shallow foundations by `swipe’ testing, International Symposium on Frontiers in Offshore Geotechnics (ISFOG), Perth, Western Australia, 469-475.
Butterfield R., Gottardi G. (2003). Determina- tion of the yield curves for shallow foundations by “swipe” testing, International Symposium on Shallow Foundations (FONDSUP 2003), Paris, France; Vol. 1, 111-118.
Gottardi G., Houlsby G.T., Butterfield R. (1999). Plastic Response of circular footings on sand under general planar loading, Géotech- nique, Vol. 49(4), 453-469.
Butterfield R., Gottardi G., Houlsby G.T. (1997). Standardised sign conventions and no- tation for generally loaded foundations, Géo- technique Vol. 47(4), 1051-1054.
Gottardi G., Butterfield R. (1995). The dis- placement of a model rigid surface footing on dense sand under general planar loading, Soils and Foundations, Vol. 35(3), 71-82.
Butterfield R., Gottardi G. (1994). A complete three-dimensional failure envelope for shallow footings on sand, Géotechnique Vol. 44(1), 181- 184.
Gottardi G., Butterfield R. (1993). On the bear- ing capacity of surface footings on sand under general planar load, Soils and Foundations, Vol. 33(3), 68-79.
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