Modification of orientation-dependency limitation for BQD index measured from exploratory drill cores in stone quarries (a case study)

ABSTRACT Various indices, notably rock quality designation (RQD), weighted joint density (WJD), and block quality designation (BQD) have been introduced by researchers to survey joints in boreholes, each with its own advantages and disadvantages. The idea of combining WJD and BQD to use positive features of both formed the main goal of the current study, leading to the definition of an improved BQD . After joint surveys of cores drilled in Kulikosh Marble Quarry, Iran, linear regressions validated by statistical tests showed that BQD is less dependent on the drilling direction than the RQD. An empirical equation was also obtained as , with the help of which one can estimate the value of by measuring the original BQD . Taking into account the joint orientations, is logically closer to reality whereby mining engineers can assess block productivity of stone quarries more accurately.