General bearing capacity theory and soil extraction method for the mitigation of differential settlements

Differential settlements experienced by a number of historic monuments have been remediated using the soil-extraction method. Italy's leaning Tower of Pisa and the Mexico City's Metropolitan Cathedral are two well-known structures where the soil-extraction method was applied to address issues associated with differential settlements. This paper describes a case study for a seven-story building in Mexico City, where differential settlements generated vertical inclinations ranging from 241-mm (9.5-in) to 310-mm (12.0-in) to the north, and 70-mm (2.75-in) to 98-mm (3.9-in) to the east. For the remediation of these inclinations, the soil-extraction method was applied through rectangular cavities excavated underneath the foundation element. The general bearing capacity theory was used to determine the location and dimensions of these cavities. After finalizing the soil-extraction process, an average settlement and upward movement of 87-mm (3.5-in) and 24-mm (1.1-in) were recorded, respectively. After the completion of the soil-extraction process, all deformations were brought within tolerable limits specified by the local building code.