Results of a jack-up measurement programme in the North Sea and their comparison with the structural analysis

Identification of jack-up spudcan fixity by an output-only substructural strategy

“…A field exercise of monitoring the dynamic behaviours and environmental conditions of three jack-up units (Monitor, Galaxy I and Magellan) was commissioned by GobalSantaFe (GSF) in the early 1990s [1,3,7]. This programme was continued with the Magellan at the Franklin and Elgin sites in the harsh North Sea [8,9].…”

“…In particular, the appropriate value of soil stiffness under jack-up spudcan footings is a hotly debated topic and an area of intense research interest within the offshore engineering community [1,2]. This debate is fuelled in large part by uncertainty in our ability to predict accurately a jack-up's physical response to its environment as well as uncertainty as to what effect that response has on the jack-up structure [3]. The level of uncertainty regarding jack-up response can be reduced if spudcan fixity can be determined.…”

“…Karunakaran et al [5] conducted an analysis of full-scale measurements from a large deepwater jack-up platform operating in the North Sea, which was the first large jack-up platform installed with skirted spudcan foundation [6]. Three jack-up drilling units in harsh environment, namely, Monitor, Galaxy I and Magellan operating in the North Sea, were monitored by permanently installed instruments [3,7,8]. Using the case records from the three jack-up units at a total of eight locations, Cassidy et al [1] determined the appropriate stiffness levels for spudcan foundations by using a trial and error method to adjust the numerical values until there was a good correlation with the measured results in both the frequency domain and the magnitude of response.…”

Effects of the Spudcan Penetration on the Adjacent Foundations

“…Therefore, the effects of the spudcan penetration on the pile or bucket foundation of platform should be considered [1]. The degree of moment restraint applied at the bottom of the leg by the soil to the spudcan is quite uncertain due to the unknown effects of the soil-structure interaction between the spudcan and the sand in seabed [2,3].…”