Updated elastic-plastic settlement prediction procedure for objects on cohesive seafloors

When a piece of equipment is placed directly on the seafloor, it is often important that its position and orientation remain stable. Depending on its characteristics and the seafloor soil properties, the item might slide, tilt or settle excessively. The analytical tools currently available in geotechnical engineering practice do not fully address the behavior of such an object in the seafloor environment, especially regarding the unusually soft and varied surface soils commonly found there. NFESC has been working on a new predictive model for foundation stability under eccentric loading for the last 3 years. In this model, the elastic modulus, previously taken as a constant, is represented as a function of soil shear strength and shear strain. In 2004, scale testing was completed and shortcomings in the predictive model were found. This paper presents an updated predictive model incorporating an augmented elastic modulus function that includes the effects of plasticity index (PI) and over-consolidation ratio (OCR).