<p>Spacing and orientation of rock joints affect stress distribution around tunnel openings. These joints provide weak planes which allow the tunnel walls to deform and converge soon after the excavation. The entire tunnel stability can be affected if unfavourable conditions exist due to persistent and closely spaced weak joints. The combined influence of joint persistency, spacing, orientation, and stiffness is critical to evaluating overall stability. This study attempts to integrate the joint characteristics and evaluate their combined effect on tunnel convergence after excavation by using a discrete element approach that explicitly models joint properties. Their effects are assessed through a statistical model based on Taguchi’s experimental design approach and ANOVA for evaluating the impact of each parameter. The effect of closely spaced and highly persistent stiff rock joints to widely spaced and weak joints of low persistence were investigated using the example of limestone rock mass properties. Joint spacing and persistency were found to influence both horizontal and vertical convergence values. Asymmetric spatial arrangement of joint sets resulted in incomplete plastic zones around the tunnel boundary and non-uniform displacement fields in all the simulations. This non-uniform displacement distribution indicated potential failure due to tensile stresses along certain joint orientations. The magnitude and direction of the normal stresses on the joint sets seem to control the rock mass deformation, leading to well-defined failure patterns. Instability prevailed when the dip angle was in the range of 60º–90º and the lateral pressure coefficient exceeded one.</p>