<p>Tunnel excavation and dam construction in jointed rock masses will disrupt the balance of forces and create new environmental conditions. Numerical modeling can be used to predict the amount of possible joint displacements and take more effective measures to stabilize the tunnel and dam structures. FRANC employs the finite element method combined with a re-mesh technique to simulate the initiation, propagation, and coalescence of cracks, based on the principles of linear fracture mechanics. The model employs the criterion of maximum strain energy for determining crack propagation. A dam with a width of 4 m was created above the model, and a rock tunnel with a diameter of 6 m was designed in the center of this model. The results show that joint angles greatly affect the crack growth pattern in a rock mass. Under conditions of fixed joint length and consistent spacing between the joint and the tunnel surface, an increase in notch angle resulted in heightened stress concentration at the notch tip. Conversely, maintaining a constant joint angle while extending the joint length led to an elevation in tensile stress measured above the tunnel. Furthermore, the differential in tensile stress between the tunnel’s roof and the adjacent rock joint showed an increase corresponding to longer joint lengths. The influence of joint length on stress distribution within rock bridges and the stress concentration near the joint is more pronounced than the effect of the joint angle. It was noted that raising the joint angle on the right side of the tunnel results in an increase in horizontal displacement. Therefore, it can be inferred that the horizontal displacement of the tunnel’s left wall is predominantly affected by the arrangement of the rock joints. These results are consistent with the instability conditions identified in dam and tunnel structures. When the notch tip is located near the tensile stress concentration areas of rock engineering structures, the interaction of tensile stress between the joint and the structure increases. This results in the initiation of new cracks at lower far-field stress levels. Conversely, when the notch tip is near the compressive stress concentration areas of rock engineering structures, stress shielding occurs at the joint’s tip, which reduces the tensile stress concentration in that area.</p>