The stability of intersection part of tunnels is greatly affected by structural planes of surrounding rockmass.Physical model testing is an effective method to study the failure mechanism of structural planes.This paper presented special section tunnel models with discontinuities by 3D printing technique to overcome the difficulty of model preparation. The failure process of the model under uniaxial loading is observed based on digital image correlation technique and endoscope. The influence of printing path on the failure mode of tunnel model is evaluated, and the influence of the dip angle of structural planes on the failure mechanism of special section tunnel is studied. Results show that printing path has marginal effect on the failure mode of the tunnel model, and it is effective and feasible to prepare the tunnel model that its failure mode controlled by structural planes using 3D printing. The non-through structural plane with weak filler transfer the surrounding rock stress to the rock pillars on both sides, which protects the surrounding rock from over-loading and improves the stability of the tunnel. When the tip of the structural plane is far away from the tunnel, the model shows the failure of the rock column caused by the through cracks. When the tip of the structural plane is near the tunnel, the model shows the separation failure of the roof block. The failure mechanism of the special section tunnel formed by the expanding excavation of the tunnel cross section is different from that of the conventional tunnel, and its arch structure effect is obviously weakened.