Extension of three-dimensional discontinuous deformation analysis to frictional-cohesive materials

• A new scheme was presented for 3-D DDA to accurately model the failure of c-ϕ joint.
• A new algorithm was developed to detect joint contacts between two polygonal faces.
• New failure criteria were proposed to improve the failure accuracy of c-ϕ joint.
• Calculated shear strengths and failure modes were identical to the analytical ones.
• The extended 3-D DDA can be used for stability analysis and movement simulations.

This paper extends three-dimensional discontinuous deformation analysis (3-D DDA) to model the frictional-cohesive failure behavior of geotechnical materials and structures. Firstly, a new contact detection scheme was developed to successfully identify the dominant sub-contacts and areas of the joints between arbitrarily shaped polyhedral blocks. Secondly, a modified joint contact model subjected to the Mohr-Coulomb failure criteria based on distributed cohesion instead of concentrated cohesion, was proposed to ensure the accuracy of the simulation by 3-D DDA. Thirdly, the extended 3-D DDA was verified by three examples, including joint contact detection, critical stability and failure mode of a system of polyhedral blocks. Finally, the complete failure process involving large displacement and rotation of multiple interaction blocks is exhibited dynamically. Overall, these examples exhibit that the extended 3-D DDA is now capable of accurately modeling the failure behavior of frictional-cohesive materials and structures, so as to optimize the material and structure stabilization or protection design.