In Dimension stone extraction of Vietnam, cutting methods, such as disc sawing and diamond wire sawing are usually deployed, because they do not make joint appearance in rock mass during cutting operation, loading to forming larger pit angle to recover more extra reserve but increasing unstable risk of pit slope when joint sets-existed rock mass (joint sets characterized by dip directions, dips and spacings). The pit slope direction is necessary to be defined to mitigate failure risk in blocky and hard rock. The paper suggested determining the pit slope directions with high failure risk to abandon in design stage or to give comprehensive solution of improving the stability when the slope in operation stage. This could be done by combination between failure Kinematic Analysis (KA) and Distinct Element Modelling (DEM) for dimension stone quarries. The paper collected Discontinuous Fracture Network (DFN) at Nui Trai Quarry for the KA of failure modes with Dips software in various pit slope directions to preliminarily show which slopes to be unstable ability under consideration of the spatial relation between joint sets and pit slopes. When pit slopes with high risk of failure is shown by the KA, they will be necessary to be analysed more deeply with the DEM, with which the DFN, pit slope directions and joint properties combined using 3DEC software. The data inputted into the software was joint sets derived from the Dips and rock mechanics at Nui Trai quarry. Combination between the two methods above will decrease the time consumption and the cost in the comprehensive stability assessment.

kinematic analysis; distinct element modelling; dimension stone quarries