Author(s): Jon E. Zufelt

Linked Author(s): Jon Zufelt

Keywords: No Keywords

Abstract: Many models have been developed that simulate ice cover progression during freeze-up or breakup. The models are typically based on equilibrium ice thickness theory and sometimes include the process of collapse and thickening. The inclusion of this process, however, is often accomplished by using general "rules of thumb. " When a certain force level is exceeded at some location in the cover, collapse and thickening occur downstream of the location of failure. Inherent in the use of equilibrium thickness theory are the assumptions of steady (or quasisteady) and uniform flow conditions. While the velocity beneath the cover may by fairly steady prior to collapse, the forces exerted on the cover are not. Certainly during collapse and thickening, most of the variables involved are highly unsteady and nonuniform. Observations from a series of experiments looking at the failure of ice covers simulated by plastic beads are reviewed. The ice cover was caused to collapse and thicken by increasing the discharge beneath the cover. Two general modes of cover failure are identified. The characteristics of the plastic beads are calculated by the theory of granular, noncohesive soils. Pre- and post-failure cover thickness is calculated using equilibrium thickness theory and compared to the experimental measurements.

DOI:

Year: 1992