THE MODIFIED BLOCK PUNCH INDEX TEST

The block punch index test, requiring only a small cylindrical disc sa mple, has been developed during the last decade and provides a practic al index in assessing the strength of intact rock. In this study, earl ier developments in the block punch index test are reviewed and a meth od for sample size correction is described. Analysis of the results, o btained from 23 different rocks, reveals that size correction in the b lock punch index test is indispensable, A strong correlation was found between the block punch index and the uniaxial compressive strength a nd strength anisotropy. Utilization of the block punch index as an inp ut parameter in rock mass classification was also suggested.