عنوان مقاله [English]
The performance of tunnel boring machines (TBM) depends on the cutters efficiency. Geological conditions and rock mass properties can influence the cutters performance. In this study, a numerical modeling, based on the discrete element method, in a 2D and 3D format, has been used to evaluate the effects of joint orientation and spacing on the fragmentation process by a TBM cutter. The considered assumptions were; constant spacing with different orientations and constant orientation with different spacing. Results show that, firstly, the critical orientation is at an angle in the range of 45 to 60 degrees, where there is a good chance to achieve the maximum rate of penetration. Secondly, critical and important joint spacing is 200 mm, where the effect of spacing on critical stress decreases significantly.