THE DESIGN AND APPLICATION OF BOREHOLE EXTENSOMETERS

Special Research Report SR-85 The high incidence of accidents resulting from ground falls in underground workings prompted this investigation into approaches which could be taken to monitor the development of fracturing in the mine roof using extensometers. A review of the instruments which were developed prior to this investigation was undertaken to determine their applicability to the monitoring of small displacements surrounding a newly formed opening. These instruments were categorized and design criteria established for the development of improved systems which would be directly applicable to the problem of inferring stability in mine roof rock.