Quasi-brittle fracture in geo-materials plays a crucial role in geotechnical engineering, and numerical methods represent a valuable approach for modeling this complex problem. This study introduces a mixed bilinear failure model considering bond effects in a modified Discontinuous Deformation Analysis (DDA) framework. Several benchmark crack-propagation problems for different materials and geometries, including three-point beam, Lshaped structure, semi-disc test and cemented granular packing, are presented to validate the novel DDA method proposed in this study. The simulation results show the accuracy of the model in predicting the mixed-mode failure of quasi-brittle materials with complex structures and assess its great potential for investigating the mechanical properties of geo-materials.
