Lava domes are conical structures that grow from the interior by the infusion of viscous magma from a central volcanic conduit. Their behavior is characterized by repeated cycles of growth punctuated by collapse as the structure becomes oversized for the strength of the composite magma that Theologically stiffens principally by off-gassing. High effusion rates result in frequent and energetic collapses, and low effusion rates result in stable growth. We explore the different growth mechanics using a two dimensional particle dynamics model. The model computes the natural evolution of a deformable talus formed by rheological stiffening driven by degassing-induced crystallization of magma, which dominates solidification. The deformable talus is modeled as a frictional material, while the softer core is cohesion dominated. Infusion rate and magma rheology together with crystallization temperature and volatile content govern the distribution of strength in the structure for the distribution of cohesive core and frictional talus. In this study the quality of the model is tested against existing experimental and observational models of lava dome growth. The DEM model follows the natural development, collapse and rearrangement of the lava dome talus, which is infeasible using simple analytical models.