Rock support can be divided into surface and reinforcement support. Surface support contain failing rocks and collects applied loads, while reinforcement support transfers collected load from the surface to competent rock away from the surface. The perfomance of rock supports is affected by several factors, such as stress regime in the sorroundings and the geology of rock. Geological structures affect the propagation of dynamic stress waves and therefore, rock support. The movement of joints by either expansion or contraction affects the propagation of stress waves and rock bolt crossing the joint. This article focuses on modeling the impact of joint mechanical and spatial properties on rock support when subjected to dynamic loading induced during blasting tests. The model used a coupling of LS-DYNA and UDEC, where LS-DYNA simulated the blasting and UDEC simulated the rock mass and rock suppports. Changes in joint parameters were studied in relations to rock support response. These changes in joint parameters affect the propagation of waves and therefore, the loading and displacement of the rock supports. Results show that rock bolts absorb large load and large deformation/displacement at joints near the surface. This study provides insight how uncertainity in geological structures can affect rock support performance.