“…In the analysis of rock block systems, an assembly of polygonal block is often formed by the intersection of joints/boundaries [9,11,20,34,45,54,58]. Compared to circular/spherical shape, the polygonal/polyhedral shape brings some difficulties for mechanical analysis of block/particle assembles, such as treatment of non-smooth contact normal change at vertices [1,5,40,55,61,62], treatment of quasi-parallel edges [63], and the contact type detection of irregular polygons with small edges or small angles.…”