Currently there is limited information about vertical shafts excavated in Chilean fine soils, which can be found in the northern zone of Santiago, this mainly due to the low number of buildings or other structures with underground excavations built in this area ( there are only a few residential and commercial buildings with underground parking lots), of which is complex to obtain information associated to their foundation designs. This study presents a simple, quick and efficient way to determine the stability of an excavation of a vertical circular shaft, which is a common structure in metropolitan subway projects. These analyzes are based on the methodology of shear strength reduction applied over an axisymmetric numerical model, validating it with analytical and numerical 3D analysis. The developed studies consider a sensitivity analysis on the cohesion parameter, incorporating "pseudo strata" of reduced cohesion in particular areas excavated, reaching the specific case of considering a clean sand lens without cohesion in each particular excavation level studied.