Experiments by Invited Researchers


Experimental Studies on Shear Failure of Freeze-Bonds in Model Ice

Project acronym: HyIII-HSVA-5-B
Name of Group Leader: Vegard Aksnes / Ada Repetto
User-Project Title: Experimental Studies on Shear Failure of Freeze-Bonds in Model Ice
Facility: Large Ice Model Basin (LIMB)
Proceedings TA Project: Experimental studies on shear failure of freeze-bonds in model ice
Data Management Report: There is no Data Management Report available for this project

User-Project Objectives

The objective of the work was to gain a deeper understanding of the freeze bond strength in model ice. Previous tests in this matter have been performed during November 2008 at HSVA. The data collected in the tests completed the data set previously measured clarifying the importance of some aspects of the experimental set up. The experiments were performed in the Cold Room of HSVA. The ice was sampled from the ice sheet grown in the big ice tank and taken to the cold room where the ice was stored and the freeze bond samples were prepared and tested. The basic set-up consisted in a direct shear testing device and a small basin provided with shelves where the freeze bonds were made. Freeze-bond strength was measured for different values of submersion time and normal confinement.

Short description of the work carried out

The complete set of experiments planned was performed. However, there was not time enough to sample properly the ice for series 3000, so the confidence in the data corresponding to the samples with 1 minute of submersion time was affected. The modifications in the direct shear device showed to improve the general performance of the tests. The bottom frame was very efficient. The upper frame can be improved to be stiffer and to avoid the application of a turning moment in the upper ice block.

Highlights of important research results

The data is less noisy and the number of samples failing in mode I (instead of the desired failure in mode II) has been reduced. Most samples failed in a brittle-like mode and the forces recorded were higher than in the previous tests performed in November 2008. The measurements at small submersion times allow to construct a complete curve of freeze-bond-shear-strength as a function of submersion time, where the expected trend (postulated in Shafrova and Høyland 2008) was found. The maximum value of the curve is between 5 minutes and 20 minutes, and the freeze-bond strength reaches a constant value (around 6000 Pa) after 4,5 hr of submersion time.

Experimental set-up to measure freeze-bond strength

Ice specimen after shear failure