ABSTRACT
By the end of June 1998, underexcavation basically eliminated differential settlements accumulated over the previous 65 years as a result of regional subsidence. When the treatment was completed, the maximum correction induced was 92 cm, between the apse and the southwestern corner. However, in September 1999 the maximum corrective settlement reduced to 88 cm and to 30 cm at the Sagrario, as shown in Figure 9.1. The reduction of corrective settlement from 92 to 88 cm was brought about, as discussed previously, by the fact that upon the end of underexcavation and the stoppage of the pumping operations, the effects of regional subsidence returned again, and as a result, part of the corrective settlements that had been achieved was lost. The net results were positive. For example, differential settlement between points C-3 and B-10 changed from 243 cm in 1989 to 156 cm by June 1998. The average angular correction between these two points was 23’ 06” and of 25’ 33” between points D-1 and A-12. Comparing Figures 8.7 and 9.1 shows that the targets set were fulfilled with underexcavation.
