Ice Shear Strength Research Articles

Adhesive shear strength of impact ice

A quasistatic experimental technique was developed to determine the adhesive shear strength of impact ices formed inside an icing wind tunnel. Parametric studies were carried out to determine the dependence of the adhesive shear strength with various factors: 1) tunnel air temperature, 2) wind speed, 3) water drop size, 4) substrate material, 5) substrate surface roughness, and 6) substrate/imp act ice interface temperature. The adhesive shear strength property was found to be statistical in nature, and on the average the mean varies between 17 and 60 psi (0.12-0.41 MPa) for rime and glaze ice, respectively. The property is also found to be strongly dependent on substrate surface roughness and substrate/impact ice interface temperature above 25°F ( —3.9°C). There is a weak statistical linear correlation between wind speed and droplet size (momentum), but the shear strength appears to be independent of tunnel air temperature, accreted thickness, and substrate material used. Comparison is made with values obtained by other investigators and differences are discussed.

Reinforced Ice and Ice Domes: Opportunities for the North*

It is suggested that reinforced ice domes in spans up to 100–150 metres and constructed by spraying water onto a spherical inflatable membrane could be economic solutions for constructing temporary enclosures in cold regions. The feasibility and practicability of such a novel and economical erection/construction technique has been demonstrated at The University of Calgary by constructing small-scale model ice domes and testing them until failure. Details of this erection technique, properties of the reinforcement (spun fibreglass yarn) and the load-deflection-time behaviour of the model domes are described. The first part of the paper gives some results on the short-duration load and creep response of unreinforced and reinforced ice samples, including shear. pull-out/bond and tensile strength. The results indicate that such fibreglass yarn reinforcement does not enhance the shear strength of ice but does inhibit initiation and propagation of cracking and thereby increase the ultimate tensile strength of the composite.

A coupled ice‐ocean model of a wind‐driven coastal flow

Ice movement driven by winds along the coast is studied using a two‐dimensional (vertical seaward), ice‐ocean coupled model. Right‐hand alongshore winds are given when internal ice stresses are important to determine the ice movement. These winds induce right‐hand coastal currents and ice movement. A shoreward Ekman flow beneath the ice is a major mechanism to constrain the ice over the shelf, balancing the internal ice pressure gradient. When the wind ceases, the ice decreases its alongshore velocity, and the ice‐covered band becomes wider. The alongshore ice velocity is sensitive to ice shear strength, which determines the shear stress at the coast; i.e., weak (strong) shear strength allows a large (small) ice velocity at the coast, resulting in intense (weak) Ekman flow and downwelling, which induces a fast (slow) coastal current. The alongshore velocity is also sensitive to the relatively small cross‐shore component of the wind; i.e., the seaward (shoreward) component reduces (induces) the shear stress and allows large (small) ice velocity. The results are applied to the ice over the Labrador shelf.

Experimental Study on Direct Shear Strength of Sea Ice

When structures such as oil drilling rigs are constructed on or through the ice plate in coastal and offshore regions, the shear strength of sea ice must be estimated to determine the loading on these structures. Testing methods for shear strength must be established so that shear strength of sea ice in various conditions can be determined.The authors have been conducting, for five years, direct shear strength experiments using sea ice samples from the Okhotsk Sea coast. Physical characteristics of sea ice, including shear strength, depend to a great extent on such properties as salinity, porosity, grain size, etc; thus, there is variation in the test results of five years experimentation since the samples obtained varied from year to year.The following conclusions were drawn from this experiment: i)Under certain conditions the relation between shear strength and vertical stress can be represented by Coulomb’s equation of soil; ie, where Ts: shear strength, C* : apparent cohesion (shear strength at σv σv = 0), φ*: angle of internal friction, σv : vertical stressii)The shear strength of sea ice increases, approaching a constant, with decreasing ice temperature.iii)The shear strength decreases with increasing ice shear area; an analogous relation exists in concrete.iv)The shear strength is not greatly dependent on either the shear velocity or stress rate.v)The shear strength is greater and generally increases more rapidly with decreasing ice temperatures in planes perpendicular to the ice growth direction than in planes parallel to it.vi)Two types of failure occurred in the sea ice samples. In the case of (sample diameter)/(sample length) less than 2 , the failure was induced by shear only. With d/l>2, the failure was not solely caused by shear since the existence of a small gap between the ice sample and shear box introduced a bending moment.

Experimental Study on Direct Shear Strength of Sea Ice

When structures such as oil drilling rigs are constructed on or through the ice plate in coastal and offshore regions, the shear strength of sea ice must be estimated to determine the loading on these structures. Testing methods for shear strength must be established so that shear strength of sea ice in various conditions can be determined. The authors have been conducting, for five years, direct shear strength experiments using sea ice samples from the Okhotsk Sea coast. Physical characteristics of sea ice, including shear strength, depend to a great extent on such properties as salinity, porosity, grain size, etc; thus, there is variation in the test results of five years experimentation since the samples obtained varied from year to year. The following conclusions were drawn from this experiment: i) Under certain conditions the relation between shear strength and vertical stress can be represented by Coulomb’s equation of soil; ie, where Ts: shear strength, C* : apparent cohesion (shear strength at σv σv = 0), φ*: angle of internal friction, σv : vertical stress ii) The shear strength of sea ice increases, approaching a constant, with decreasing ice temperature. iii) The shear strength decreases with increasing ice shear area; an analogous relation exists in concrete. iv) The shear strength is not greatly dependent on either the shear velocity or stress rate. v) The shear strength is greater and generally increases more rapidly with decreasing ice temperatures in planes perpendicular to the ice growth direction than in planes parallel to it. vi) Two types of failure occurred in the sea ice samples. In the case of (sample diameter)/(sample length) less than 2 the failure was induced by shear only. With d/l>2, the failure was not solely caused by shear since the existence of a small gap between the ice sample and shear box introduced a bending moment.