Slip Line Field Solutions as an Approach to Understand Ice Subgouge Deformation Patterns

• Main Authors: Ima S S Schoonbeek, May X Xin, Walther G M Van Kesteren, Ken Been
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1035.5246; http://www.isope.org/publications/proceedings/ISOPE/ISOPE%202006/papers/2006_JSC_472.pdf

ABSTRACT In the Arctic where drifting ice contacts the sea floor, oil and gas pipes need to be buried at a certain depth beneath the sea floor to avoid damage caused by ice scour and the soil plastic deformation induced by ice scour. For a safe design, knowledge is required about the depth and magnitude of the soil deformation, referred to as the subgouge. This paper presents the centrifuge testing results of subgouge deformation and examines the viability of using slip line field solutions as a theoretical approach to estimate the subgouge deformation induced by ice scouring. For centrifuge testing, variables included ice keel speed, undrained shear strength of soil and ice keel scour depth. The soil deformations were determined by image processing of video camera data; and the horizontal and vertical loads were measured using load cells. For the theoretical approach, Petryk's (1987) slip line field solutions for a rigid wedge sliding over a flat surface of ductile material are used as an analogy to the processes occurring in ice scouring, where ice is the rigid hard material and soil is the ductile material. Investigation shows the deformation mechanism in Petryk's slip line field solutions resemble what was observed during model tests of ice scouring in clay. The results from the slip line solutions are compared with the testing data. Discussions on the validity of the theoretical approach and empirical equations are presented.