Journal of Cold Regions Engineering

A series of in-situ flexural strength and cyclic stress tests were carried out on laboratory-prepared NaCl ice beams, whose average growth rates exceeded those of sea ice. The flexural strengths were all found to be within the accepted range for sea ice, with those beams grown at the slowest rate being strongest, confirming our use of NaCl ice as a sea ice analog. The direction of loading had no observable effect on either the flexural strength or the tangent modulus. An S-N diagram showed no evidence of a fatigue limit nor any significant difference for two different loading frequencies (0.11 and 0.06 Hz). There was no significant dependence of N on porosity of the ice. Loss tangents were typically in the range 0.15–0.25, remaining relatively constant over the duration of the test. The tangent modulus showed considerable variation over the beam population as a whole, and for individual beams decreased steadily over the duration of the test. The loss tangent and tangent modulus showed transient effects for some beams and not others.

The term “effective strain rate” is frequently encountered in literature devoted to the ice-structure interaction problem. As a rule, it is defined as a ratio between indentation velocity and structure width, multiplied by a certain nondimensional factor (αV/d). Usually this parameter is used to separate different interaction regimes or different types of ice behavior during the indentation process. The concept of an effective strain rate, $(\dot{\epsilon }$_esr) seems to be quite useful because it allows the comparison of the results of experiments conducted at different scales if $\dot{\epsilon }$_esr is properly defined. What is more, the correct definition of $\dot{\epsilon }$_esr may help to apply the results obtained on the basis of small-scale laboratory tests to real ice-resistant structures. On the other hand, the overall concept of an effective strain rate definitely lacks a fundamental basis and there is no consensus on the value of the nondimensional factor α. The present paper discusses various approaches to the definition of $\dot{\epsilon }$_esr and gives a few analytical expressions for $\dot{\epsilon }{}_{\mathrm{esr}}$ derived for different indentation problems.

In areas where damaging spring breakup ice jams are recurring events, advance mitigation measures should be considered. One mitigation measure that might be used in advance of ice breakup is aerial dusting of the ice, which enhances the natural weakening process. Because there may be limited time in which to organize and implement advance measures for ice jams, dusting operations should be planned beforehand. This paper provides a brief overview of the physical processes involved in ice dusting and discusses important aspects of a dusting plan. Experiences from two dusting programs in Nebraska were used as the basis for developing a set of guidelines for planning dusting operations. A spreadsheet for estimating dusting costs was also developed, and is presented with actual data from a 1994 dusting operation.

Linear and nonlinear viscoelastic constitutive equations for freshwater and sea ice are addressed. Following a brief review of linear theory, some recently developed, physically based nonlinear equations are discussed, considering elastic, viscous and delayed elastic strain components. It is observed that a broad time spectrum representation is needed for an adequate characterization of the delayed elastic strain in the linear and nonlinear ranges of behavior. A specific nonlinear constitutive equation for uniaxial loading is proposed and successfully applied to the strain response of S2 saline ice subjected to multiple cycles of in-plane tensile loading and unloading. The theory is then extended to multiaxial loading.

A series of experiments were conducted to determine the force required to scrape ice from portland cement concrete (PCC) and asphaltic concrete (AC) samples. The force was measured as a function of cutting-edge geometry (especially rake angle), the scraping velocity, and the applied download. The results indicate that the rake angle has no significant effect on the scraping force, whereas the download has a clear effect, with scraping force increasing with download. An increase in the scraping rate caused the scraping force to decrease for the PCC samples, but not for the AC samples. The results are compared with those obtained for negative rake angles in another study.