Author(s): Steven F. Daly
Linked Author(s): Steven F. Daly
Keywords: No Keywords
Abstract: The stresses induced in ice covers by river waves are investigated as a possible mechanism for causing transverse cracks during breakup. The maximum stress levels that river waves can cause in the ice cover are determined over the entire spectrum of waves that may be present at breakup, from very long kinematic or flood waves, to very short pressure waves. The ice cover is analyzed as a continuous elastic plate, with only vertical bending in the longitudinal direction being considered. For a given wave amplitude, the amplitude of ice-cover bending stress has two possible maximums: one when the wavelength is equal to. .. (where i is the characteristic length of the ice cover) and a second when the celerity of the propagating wave equals the celerity of a free (homogeneous) wave in the ice plate of the same wavelength. This second maximum is entirely analogous to the "critical" wave speed effect caused by a moving load on a floating ice sheet The present calculations indicate that the celerities of waves propagating in an ice-covered channel are always less than the celerity of free waves of the same wavelength, and, as a result, only the. .. maximum is possible. The global minimum wave amplitude required to cause cracks in the ice cover is therefore found at a wavelength of 'btl. At this wavelength, a particularly simple expression describing the minimum wave amplitude causing cracks can be derived; and for reasonable values of the ice properties, this amplitude is quite modest A possible mechanism for producing waves with wavelengths near. .. during dynamic ice cover breakup is then outlined, along with strategies for detecting these waves.
Year: 1994