A new algorithm to identify contact types between arbitrarily shaped polyhedral blocks for three-dimensional discontinuous deformation analysis

In the contact theory for three-dimensional discontinuous deformation analysis (3-D DDA), the first step is to identify the types of contacts between the blocks. This paper presents a new algorithm to identify contact types between arbitrarily shaped polyhedral blocks for 3-D DDA. First, pairs of neighbouring blocks that are close enough to possibly be in contact are recognized using their axis-aligned bounding boxes. Four types of dominant contacts (i.e., vertex-to-vertex, vertex-to-edge, vertex-to-face and crossing edge-to-edge contacts) that control the movements of blocks, especially rotations, are then identified using an extended hierarchy territory algorithm. Finally, using a new loop search procedure, face-to-face contacts in which the interface strength depends on the friction angle, cohesion and tensile strength rather than only the friction angle, are formed from several interdependent dominant contacts. The results of three numerical examples demonstrate the ability of the new algorithm to address the complex problem of contacts between arbitrarily shaped polyhedral blocks.