عنوان مقاله [English]
Brittleness is one of the most important mechanical properties of rock that is widely used in geotechnical designs such as drilling operations and underground structures. So far, standard method for estimating the brittleness of rocks have not been introduced and therefore, indirect methods are used to estimate them. In this research, brittleness of granitic rocks are estimated from Schmidt hardness and petrographic characteristics (minerals mean size and mineralogical composition) using simple and multivariate statistical relationships. To achieve these goals, 10 different granite rocks were collected from quarries Tavandasht and Gosheh around Borujerd (Lorestan province). Based on laboratory tests, brittleness index, Schmidt hammer hardness, minerals mean size and quartz to feldspar ratio were determined. Then, different models were fitted to the data for estimating the brittleness.The results of simple statistical relationships indicate that there are moderate correlations (determination coefficients ranging from 0.70 to 0.87) between the brittleness index with Schmidt hammer hardness, minerals mean size and quartz to feldspar ratio. While the multivariate statistical relationships indicate a significant effect of the minerals mean size and quartz to feldspar ratio on the accuracy of correlation between the brittleness index with Schmidt hammer hardness s (with determination coefficients of 0.91 and 0.93, respectively).