Influence of Parallel Joint Spacing and Rock Size on Rock Bulk Modulus

The size effect on the bulk modulus of rocks has been reported by previous studies. The accuracy in selecting the parameter for the rock mechanics analysis determines further accuracy of the calculation results. Moreover, given the influence of the size effect and joint spacing, the rock bulk modulus often changes. Thus, it is essential to examine the size effect on the bulk modulus. This study elucidated the influence of rock size and parallel joint spacing on the bulk modulus using the regression analysis and 12 sets of numerical plans. The results demonstrated that the bulk modulus decreased with an increase in rock size, and the curve represents an exponential function. The bulk modulus linearly increased as the parallel joint spacing increased. Furthermore, the characteristic size of the bulk modulus linearly decreased as the parallel joint spacing increased. In contrast, the characteristic bulk modulus linearly increased as the parallel joint spacing increased. The specific forms of these relationships were also elucidated in this study.