Excavatability Assessment of Rock Masses for Geotechnical Studies

The excavatability of rocks is of importance for the selection of suitable and cost–effective excavation methods not only in mining and quarrying but also in the construction of tunnels, subways, highways and dams. Moreover, selection of the right excavation method and equipment in mining and geotechnical projects depends on the excavatability properties of rocks. A number of different methods have been proposed to evaluate the excavatability of rocks based on their geotechnical properties, such as rock mass rating (RMR), uniaxial compressive strength (UCS), discontinuity spacing of rock masses, point load index (PLI) and seismic velocity of intact rock. The type of equipment used and the method of working also affect the excavatability of rocks. In this work, the term excavatability is considered as the ease of excavation of rock and rock masses and comprises the methods of digging, ripping, breaking and blasting for easy/very easy, moderate to difficult, soft or moderately to highly fractured rock and very difficult excavation conditions, respectively.

Block Volume Estimation from the Discontinuity Spacing Measurements of Mesozoic Limestone Quarries, Karaburun Peninsula, Turkey

Block volumes are generally estimated by analyzing the discontinuity spacing measurements obtained either from the scan lines placed over the rock exposures or the borehole cores. Discontinuity spacing measurements made at the Mesozoic limestone quarries in Karaburun Peninsula were used to estimate the average block volumes that could be produced from them using the suggested methods in the literature. The Block Quality Designation (BQD) ratio method proposed by the authors has been found to have given in the same order of the rock block volume to the volumetric joint count (Jv) method. Moreover, dimensions of the 2378 blocks produced between the years of 2009 and 2011 in the working quarries have been recorded. Assuming, that each block surfaces is a discontinuity, the mean block volume (Vb), the mean volumetric joint count (Jvb) and the mean block shape factor of the blocks are determined and compared with the estimated mean in situ block volumes (Vin) and volumetric joint count (Jvi) values estimated from the in situ discontinuity measurements. The established relations are presented as a chart to be used in practice for estimating the mean volume of blocks that can be obtained from a quarry site by analyzing the rock mass discontinuity spacing measurements.