EFFECT OF FATIGUE ON THE BEARING CAPACITY OF FLOATING ICE SHEETS

Laboratory tests on floating freshwater ice covers with specially buil t pulsators are described. Preliminary tests showed that the creep def lections were very small and that the pulsator used did not cause a br eakthrough on its own in the time frame considered. Therefore, a break through method was used to determine the effect of the oscillatory loa d on the bearing capacity of an ice cover. After a prescribed time (or a number of accumulated cycles) both loading devices, the pulsator an d its static control, were subjected to a constant downward deflection rate by means of screwjacks until breakthrough occurred. Two series o f tests were conducted, one at an oscillating frequency of 21.5 Hz and the other at 15 Hz. Results of both series of test showed that the os cillations substantially lowered the bearing capacity of the ice cover s tested.