Abstract: The structural geomaterials was idealized as an assembly of oval blocks.Under the loading the oval blocks gradually broke in three modes,i.e.,local crushing,shearing rupture and bending rupture,and the respective criteria of breakage were deduced.The process of breakage could be divided into five stages.The stress-strain curves and the evolution of breakage parameters were obtained when the blocks were arranged in a regular way with maximum void ratio,and the anisotropic behavior of such an assembly was confirmed from these calculated results.