Size distribution and shape characteristics of ice electromechanical auger drill

摘要

The size distribution and shape characteristics of ice cuttings have a large influence on the efficiency of the transportation of cuttings by electromechanical auger drills and eventually determine the maximum possible rate of penetration. The size of ice cuttings is usually controlled and estimated by visual examination, but this is insufficient for the precise control and prediction of performance of ice cutting removal. To determine the patterns of ice cuttings, sixteen ice cuttings were sampled in the course of drilling in natural lake ice by an electromechanical auger drill at a temperature below -5 degrees C. The cutter is 19 mm in width, with a rake angle of 45 degrees and a relief angle of 15 degrees. Sensors are employed to measure the drilling-depth, drilling-time and rotation speed of the coring auger. This paper presents the size distribution and shape characteristics of cuttings under various drill head rotation speeds and rates of penetration by using a sieving and computer image-based method. The size distribution of the cuttings has an asymmetrical shape similar to a chi-square distribution. Approximately half of the ice cuttings by weight are classified as small sized (<0.6 mm). In all of the sieving samples, the ice cuttings have prolate form with a ratio between the major and minor axis within the range of 1.35 to 1.97, averaging similar to 1.55. (C) 2015 Elsevier B.V. All rights reserved.