Drilling practice in the field of grouting : Littlejohn, S Ground Engng, V12, N1, Jan 1979, P39–43, 52–53

Abstract

In the specialist area of drilling and grouting, particularly within the fields of civil and mining engineering, drill holes with diameters of 50 to 300mm, and depths ranging from 3 to 300m, appear to cover the majority of applications. Any drilling machine or procedure which can supply a stable hole of adequate dimensions within the permitted tolerances and free of obstructions or protrusions may be employed. In this regard the method of drilling and type of equipment are chosen primarily with respect to: (a) diameter and depth of hole, (b) nature of ground material and mass structure, (c) borehole interface requirements, (d) availability and suitability of flushing medium, (e) drilling rate required, and (f) accessibility and topography of the site. The following sections provide a brief personal view of present practice and its shortcomings in relation to these major choices, which have to be made by the grouting specialist. Both drilling and grouting are specialist topics which have been practised for many decades. Although technical advances have been made over the years, the subjects when applied to the ground are still steeped in tradition and rules-of-thumb. As a consequence individuals invariably argue from subjective or entrenched positions, often based on general experience and qualitative assessments. These so called specialists seldom agree. To progress from this position, case histories on drilling are required where the ground has been properly classified, and the drilling performance monitored in terms of rate of advance, torque, rotational speed, axial crowd force, flushing medium and amount of flush, for a given size of hole and range of depths. In this way factual information will be compiled and permit the basic principles of drilling to be reviewed. Only in this way can the art of drilling be drawn into the discipline of engineering. /Author/