The behaviour of the liner-rock interface is an important property which determines the support characteristic of polymer-based rock support systems. The interaction between the liner and the rock substrate was defined using a traction-separation description of a cohesive zone model in ABAQUS. A cohesive zone model was developed in this study to simulate a double-sided shear test. The shear behaviour observed in the double-sided shear test of a polymer-plaster assembly was characterised by two stages, elastic behaviour of the shear bond before the peak stress and the gradual failure of the shear bond in the post-peak region. The initiation of shear bond failure was defined using a stress-based criterion. The post-peak behaviour was simulated by introducing a damage variable. An exponential damage law was considered to model the evolution of the damage variable from the initiation to complete failure of the shear bond. The parameters for defining the cohesive law were taken from experiments carried out at the University of Wollongong. The damage variable to define the damage evolution law was determined using back analysis. A parametric study was carried out with different values of the damage variable and the results obtained were compared against the experimental result. Finally, a three-dimensional numerical model was developed using the calibrated parameters. The failure behaviour of the interface in the double-sided shear test was simulated accurately, and evolution of the exponential damage variable was also explained. The results observed in the numerical model were found to be in agreement with the experimental result.