A Comparative Assessment of the Use of Spudcans and Caissons as the Foundations of Jack-Up Structures

2005 ◽  
Author(s):  
G. Vlahos ◽  
M. J. Cassidy ◽  
B. Knowles
Keyword(s):  
Comparative Assessment ◽  
Shallow Foundations ◽  
Clay Sample ◽  
Overall Response ◽  
Caisson Foundations ◽  
Jack Up ◽  
Overconsolidated Clay

More than ever before, operators are advancing mobile jack-up units into deeper waters and harsher environments. Constraining their use is the capacity of the shallow foundations (typically inverted conical spudcans) to withstand the larger wave, wind and current loads of these environments. The use of foundation skirts (or caissons) is often touted as an alternative, though today only a small percentage of jack-up units use caisson foundations. One restraining feature is limited understanding of their behaviour when compared to conventional spudcan. This paper addresses this by comparing the results of push-over experiments of a three-legged jack-up with similarly sized caisson and spudcan foundations. The tests were conducted on a 250:1 scale jack-up on an overconsolidated clay sample. With improved understanding of the overall response of a jack-up platform with caisson foundations, operators should have greater confidence to use these footings.

Push-Over Response of a Jack-Up on Sand of Different Relative Densities

2009 ◽  
Author(s):  
Britta Bienen ◽  
Mark J. Cassidy ◽  
Christophe Gaudin
Keyword(s):  
Wind Waves ◽  
Scaled Model ◽  
Environmental Loading ◽  
Complex Load ◽  
Geotechnical Centrifuge ◽  
Overall Response ◽  
Load Paths ◽  
Numerical Predictions ◽  
Macro Element ◽  
Jack Up

On location offshore, jack-up structures are subject to environmental loading from wind, waves and current in addition to self-weight. Over the operational period of the jack-up, the environmental loading on a given site may not be unidirectional along the jack-up’s ‘axis of symmetry’ but may act from different directions and/or be non-collinear (i.e. wind acting from a different direction than waves and current), resulting in complex load paths at the spudcan footings. This paper discusses load paths obtained from experiments on a scaled model jack-up for two different horizontal loading directions and illustrate the implications of spudcan load paths for the overall response of a jack-up to failure. Similar tests were performed at two different relative sand densities, allowing the influence of relative density on jack-up behavior to be investigated. Similitude to the prototype was achieved by conducting the experiments in a geotechnical centrifuge at 200g. The paper concludes with numerical predictions of the experimentally measured response, using a macro-element to model the soil-spudcan interaction coupled to a structural finite element program. The footing macro-element has been developed based on plasticity theory and single footing experiments, but its ability to predict the respective load paths of each of the spudcans in a multi-footing system is demonstrated here. The paper further provides the experimentally measured jack-up push-over capacity and numerical predictions in the context of recommendations of current guidelines. This highlights the requirement of nonlinear elasto-plastic modelling of the load-displacement behavior of the jack-up foundations in order to predict the overall response of the system.

Effects of Drained Pre-Loading on the Performance of Shallow Foundations on Overconsolidated Clay

2005 ◽  
Author(s):  
B. M. Lehane ◽  
C. Gaudin
Keyword(s):  
Bearing Capacity ◽  
Carrying Capacity ◽  
Design Guidelines ◽  
Shallow Foundations ◽  
Load Carrying Capacity ◽  
Numerical Predictions ◽  
Standard Design ◽  
Load Carrying ◽  
Overconsolidated Clay

This paper presents results from a programme of centrifuge experiments which examined the effects of drained preloading on the stiffness and load carrying capacity of shallow square footings founded on an overconsolidated clay. The increases in stiffness and bearing capacity induced by various levels of preloading are quantified and compared with standard design guidelines and previously published numerical predictions.

Suction Caisson Foundations for Offshore Wind Turbines

2002 ◽  
Vol 26 (3) ◽  
pp. 145-155 ◽  
Author(s):  
Byron Byrne ◽  
Guy Houlsby ◽  
Chris Martin ◽  
Peter Fish
Keyword(s):  
Design Process ◽  
Wind Turbines ◽  
Research Council ◽  
Shallow Foundations ◽  
Offshore Wind ◽  
Physical Sciences ◽  
Suction Caisson ◽  
Offshore Wind Turbines ◽  
Caisson Foundations ◽  
Suction Caissons

This paper outlines a £ 1.5m, three year, research project that commenced during the middle of 2002 to determine a design framework for shallow foundations for offshore wind turbines. The shallow foundations in focus are suction-installed skirted foundations otherwise known as suction caissons (Houlsby and Byrne, 2000). There are eight distinct themes to the research covering all aspects of the geotechnical performance of these foundations. The funding for the project has been obtained from the Department of Trade and Industry (£ 917k), Industrial Partners (£ 373k) and the Engineering and Physical Sciences Research Council (£ 221k). The results will feed into the design process for offshore wind turbines almost immediately.

Development of biotechnology for gluten-free sourdough bakery products with a new microbial composition

2020 ◽  
Vol 29 (12) ◽  
pp. 59-63
Author(s):  
O.I. Parakhina ◽  
◽  
M.N. Lokachuk ◽  
L.I. Kuznetsova ◽  
E.N. Pavlovskaya ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Starter Culture ◽  
Comparative Assessment ◽  
Starter Cultures ◽  
Bakery Products ◽  
Gluten Free ◽  
Microbial Composition ◽  
Fermentative Activity ◽  
Theoretical Foundations

The research was carried out within the framework of the theme of state assignment № 0593–2019–0008 «To develop theoretical foundations for creating composite mixtures for bakery products using physical methods of exposure that ensure homogeneity, stability of mixtures and bioavailability of nutrients, to optimize diets population of Russia». The data on the species belonging of new strains of lactic acid bacteria and yeast isolated from samples of good quality gluten-free starter cultures are presented. A comparative assessment of the antagonistic and acid-forming activity of strains of lactic acid bacteria and the fermentative activity of yeast was carried out. The composition of microbial compositions from selected strains of LAB and yeast was developed. The influence of the starter culture on the new microbial composition on the physicochemical, organoleptic indicators of the bread quality and resistance to mold and ropy-disease was investigated.

Mapping slope deposits depth by means of cluster analysis: a comparative assessment

2016 ◽  
Vol 39 ◽  
pp. 47-50
Author(s):  
Tiziano Venturini ◽  
Emanuele Trefolini ◽  
Edeardo Patelli ◽  
Matteo Broggi ◽  
Giacomo Tuliani ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Comparative Assessment ◽  
Slope Deposits
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