Pull Tests as a Measure of Roof Bolt Efficiency and of Roof Bolt Design AND Roof Bolt Anchorage at Michel Colliery AND Roof Bolting Practices, Dominion Coal Company Limited, Sydney, N. S. AND Discussion - Forum on Roof Bolting AND Roof Bolting Effectivene

A variety of practical tests have been tried in the mining industry to determine the support properties of mine roof bolts. Such tests include torsion wrench readings, hammer blow tests and the use of plates with built-in tension indicators. This paper gives some details of pull tests with a hydraulic jack, as carried out in coal mines of western Canada. AND The use of roof bolting gave promise of substantial economic benefits to Continuous Miner operations at Michel Colliery. As the first step in the adoption of bolting, 142 anchorage tests, employing six types of anchor shells, were made in three mines. Significant differences were found in the anchorage capabilities of the various shells and the various roof rocks. AND Since 1950, a total of 164 miles of levels and rooms have been roofbolted in the collieries of the Dominion Coal Company. Roof bolting is an efficient and economic method of support where heavy timber sets or steel booms are necessary for temporary roof support, or where conventional methods of support interfere with the passage of mechanical mining equipment. This paper discusses present roof bolting practices and special bolting applications. AND Crows Nest Industries Limited adopted roof bolting in 1963 to improve roof control and to extend continuous miner utilization in one mine. Bolting was held back because anchorage tests gave inconsistent results. The time lapse between mining and bolting was suspected as a cause, and so a test entry was driven and sections of it were bolted as part of the work cycle in addition to the normal timbering. This paper presents the results of the instrumentation of test entries and discusses the utilization of the data to improve mining procedure