Underexcavation for Leveling Buildings in Mexico City: Case of the Metropolitan Cathedral and the Sagrario Church

Underexcavation has been used in Mexico City to reduce differential settlements in buildings. This paper describes a case history in which the method was applied successfully: the Metropolitan Cathedral and the adjoining Sagrario Church, which settled differentially because of self-weight consolidation and regional subsidence. Underexcavation, which took place between August 1993 and June 1998, was adapted to the particular conditions in the site, and the procedure was followed using extensive instrumentation in order to apply the observational method to control it. Maximum corrective settlements attained with underexcavation were more than 90 cm. Stepwise, the procedure is shown to be an advantageous technique for reducing differential settlements and tilts when obtrusion of the structure cannot be tolerated.