This deep excavation tutorial shows the modeling process of a 26-meter excavation using the COMSOL Multiphysics Geomechanics Module. A parametric sweep is used to simulate the excavation steps in the soil, and a Drucker-Prager criterion is used for studying the soil plasticity. Using the Solid Mechanics interface, the interactions between the soil and the retaining wall are calculated and the results are shown. The results consist of two 2D plots: the deformation of the soil and retaining wall, and the plastic deformation. Additionally, two 1D plots show the wall deflection and surface settlement.