Two parallel tunnels are used in the field of underground construction not only in Vietnam but also in other countries around the world. Currently, two-tunnel analysis problems are resolved based on simple assumptions, such as circular tunnels in an elastic, isotropic, and continuous environment of rock mass under flat surface conditions. However, many types of different cross-sections of tunnels have been used depending on the intended use of the tunnel and the tunneling technology. The geological conditions are very complicated, consisting of joints, layers, faults, and other parameters. Additionally, there are many different types of tunnel cross-sections, such as arch, horseshoe, curved rectangle, elliptical, oval, and other shapes, and the topographical surface conditions are also complex. This problem requires in-depth research to ensure effective excavation, protection, and utilization of tunnels. This article analyzes the alteration of displacement and stresses around tunnels with different cross-sections under sloped surface conditions using numerical models to select an appropriate tunnel shape. The research results show that under both flat and sloped surface conditions, the suitable tunnel shapes are horseshoe or sub-rectangular, as these shapes minimize displacement along the tunnel boundaries.