Optimization of ice cuttings transportation by cable-suspended core auger drills

Ice cores contain an abundance of information about the Earth's climate in the past , and recovered from shallow drilling down to 300- -350 m give sufficient information for reconstructing of the last climatic chan- ges and for monitoring of pollution from human being. Cable-suspended core auger drills use an armored cable with a winch to provide power to the down-hole motor system and to retrieve the down-hole unit. Because of their lightweight , convenient transportation and installation , high penetration rates and low power consumption , core auger drills are widely used for shallow drilling in ice. Nowadays at least 14 types of auger electromechani- cal drills were designed and tested in different foreign and national glaciological laboratories. However , auger options were usually determined by experience , and the main parameters ( helix angle of the fights and rotational speed ) are varied in a wide range from drill to drill. If parameters of auger are not chosen properly , poorly en- gineered drills had troubles with low efficiency of cuttings transportation , jam of ice cuttings , repeated fragmen- tation , cutters icing and stop penetration , abnormal power consumption , high rotation torques , and so on. Thus , this paper presents the method of optimization of ice cuttings transportation of cable-suspended core auger drill on the base of the theory of rotary auger. As the result , the optimal helix angle was determined correspond- ing to the rotational speed from the transportation efficiency point of view.