Experimental study of dynamic conical ice force

Abstract

Dynamic ice force is one of the key factors in the design and operation of narrow offshore structures in ice-covered areas. In the paper, a series of physical model tests were carried out to simulate field ice conditions on the oil jacket structures with an ice breaking cone in the Bohai Sea. The model tests involved two geometric scale factors (3 and 6), 3 structural models, and 3 ice sheets. In the total 17 groups of tests, the controlled parameters of ice velocity, ice friction coefficient, and the shape of the ice-resistant structure at the waterline were different. The time history of ice forces, accelerations of the model, and the ice–cone interaction process were recorded synchronously. Ice failure modes and global ice loads obtained from the model tests were compared with the data measured on the JZ20-2MUQ oil jacket platform. Similar to the results in the field measurements, two ice failure modes were observed on the cones in the lab test. The plate failure mode was observed on the inverted cone. For the upright cone, when the cone diameter was increased, the ice failure mode was transformed from the wedge failure mode into the plate failure mode and the ice load on unit area was decreased.