Design ice load for piles subjected to ice impact

Design loads of offshore structures for ice-covered seas are typically based on ice-crushing approach. It always, therefore, makes the design conservative, especially for the loads on vertical offshore structures exerted by moderate ice mass. Taking the case of sheet-pile-type pier, we conducted a series of tests of ice loads on cylindrical piles subjected to the impacts of drifting ice. The objective is to develop the relationship between ice kinetic energy and the impact force, and finally to establish the design ice load for the piles. An envelope of logarithm curve was applied to determine the design load on the piles. The envelopes of ice force with known compressive strengths with respect to ice kinetic energy were used to determine the expected peak loads. The expected peak loads with different ice uniaxial compression strength were used to form another envelope to establish the design load on an individual pile for a special compressive strength. With the same approach, the total ice force on one pier unit was obtained from an envelope curve. The design load on an individual pile can be applied to real ice as its scaled kinetic energy and compressive strength range from 0 to 0.8 J and 30 to 90 kPa. Considering the large force on the corner pile, special tests of force against the pile were conducted. The results showed that the design load on the corner pile is 0.78 times that of one dock unit, and 1.69 times that of the other six piles. Therefore, the corner pile should be reinforced in engineering applications.

► Impact ice forces with different velocity on piles were measured. ► Envelop method is applied to determine the design loads on piles. ► Design load on the corner pile is considered apart from the others. ► The corner pile should be reinforced for engineering applications.