Development of a Rotational Shear Vane for use in Avalanche Safety Work

Development of a Rotational Shear Vane for use in Avalanche Safety Work

Abstract

This Masters Thesis describes the continuation of the Snow Probe development. The focus of this project was to establish the rotational shear vane as a useful tool in avalanche safety work as well as develop a robust method for measuring the applied torque.

A new and novel way of measuring the torque on a rotational shear vane has been developed to illustrate its effectiveness. The new system measures the power supplied to a cordless drill to get an indication of the applied torque. This was done because it was found that the earlier method of using a strain gauge/cantilever system repeatedly failed to work, largely due to complexity.
The snow probe in its present embodiment has been shown to provide a good clear indication of the snow profile under easily repeated circumstances. Shear strength results are at this stage not sufficiently for reliable quantitative results. However the probe in its present form is able to give pictorial impressions of the snow pack that compare well to current hand hardness profiles derived from snow pit methods. Even in its current form the snow probe is able to collect useful snow profile data in a matter of minutes, much quicker than conventional snow pit methods.

A loose relationship was found to exist between the approach angle of a shear vane blade and the clarity of the snow profile. These relationships are relatively inaccurate at present due to lack of rotational velocity data and therefore approach angle data. It is believed that the addition of a rotation counter would greatly increase the accuracy of the probe results and enable a shear strength profile to be quantified.