Abstract: A 3D irregular deformable discrete element model isdeveloped to model the brittle failure process of rock materials. Under theexternal loadings, continuous blocks near the failure limitsare cut into several smaller blocks, and connect-type springs areassigned on the interface between these blocks. Under the tension-shear failurecriterion, the connect-type springs are broken into the contact-typesprings. As a result, a continuous-discontinuous modeling of brittle failureof rock materials is implemented. Dynamic relaxation technique is applied toobtain solutions without assembling the global matrix. The model is validated by typical examples.