ROCK MASS CLASSIFICATION FOR KARST LIMESTONE OF CAMBODIA FOR BLASTING

Karst limestone deposits are found worldwide with ten percent of earth’s surface consisting of karst topography having sinkholes or dolines and caves. Limestone deposit under study is of Permean age located in southern part of Cambodia. Rocks are generally classified based on uniaxial compressive strength (UCS), direct shear strength (DSS) rock quality designation (RQD), rock mass rating (RMR), Dry Density (DD). Geomechanics classification is based on spacing, condition and orientation of discontinuities, ground water condition. Geomechanics properties of rock mass plays important role in blasting performance such as powder factor, throw, fragmentation, back break and flyrock. Based on regional lithology of Cambodia, limestone is classified as semi marble, agillaceous, chetty and micrtic limestone. Karst topography is divided into undeveloped, normal, mature, complex and extreme karst. 25 core samples each were selected and tested for UCS, DSS, DD from study area. During initial stage of mining project, detailed information on limestone deposit may not be available. The proposed methodology of rock mass classification is based on review and will be useful for blast design and prediction of blast performance at Cambodian limestone deposit.

Rock Mass Classification, Rock mass rating, Karst topography, Blast design, Blast performance.