Assessing appropriate stiffness levels for spudcan foundations on dense sand

作者：Cassidy Mark J^*; Vlahos George; Hodder Mathew

来源：Marine Structures, 2010, 23(2): 187-208.

DOI：10.1016/j.marstruc.2010.03.003

• Jack-up
• Spudcan foundations
• Stiffness, footings/foundations
• Plasticity
• Model tests
• Soil-structure interaction
• Sand

Before a jack-up can operate at a given location, a site-specific assessment of its ability to withstand a design storm during operation must be performed. During this assessment, the complex state of stress and strain under a spudcan is usually simplified to a value of foundation stiffness that is integrated as a boundary condition into the structural analysis. Soil stiffness is a critical parameter affecting the foundation and structural load distribution and displacements, and the jack-up natural period and dynamic response. The level of spudcan stiffness is an area of intense interest and debate. This paper assesses appropriate stiffness levels for numerical simulation. Utilising results from a detailed "pushover" experiment of a three-legged model jack-up on dense sand, the paper compares the experimental pushover loads and displacements on the hull and spudcans to numerical simulations using different assumptions of spudcan stiffness. These include pinned and encastre footings, linear springs and a force-resultant model based on displacement-hardening plasticity theory. Constant stiffness levels are shown to be inadequate in simulating the experimental pushover test. The non-linear degradation of stiffness associated with the latter force-resultant model is critical.

• 出版日期2010-4