Foundation Scour as a Geohazard

Abstract

Carrying out a hazard assessment for offshore structures can entail the consideration of a number of different factors. Scour hazard assessments are routinely undertaken, and scour development at offshore structures should be considered a time-varying process. However, scour may take place within a morphologically dynamic environment, the combination of which will impact on the soil-structure-fluid response. This paper presents the analysis of an unique data set that shows the partial collapse of a scour hole at a large monopile foundation within a morphologically active site. The collapse suggests a slope failure mechanism resulting in the movement of around 450 m3 of material within a period of about 75 minutes. The paper analyses the processes involved regarding formation and development of the collapse.

Scour Effect on the Lateral Bearing Behaviour of Monopiles Considering Different Slenderness Ratios

“…Monopiles in the offshore marine environment are prone to scour. The mechanism is that the soil within a certain area in the vicinity of the pile is washed away by waves and current, reducing the lateral capacity of the pile and changing the structural stiffness and system frequency [3][4][5][6][7][8][9][10][11][12][13][14][15]. Two monopiles at the Robin Rigg wind farm were decommissioned after only six years of operation due to massive unexpected scour, demonstrating the hazard that the active marine environment poses to OWTs [16].…”