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Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Table 1. Monuments types subjected to systematic study (from Cecconi
et al. 1997).
a)
b)
Figure 11. An analysis of some Italian monuments (modified from
Cecconi et al. 1997): a) damage types; b) preservation measures.
However sometimes the causes of the instability are not clear
and the possibility of removing them remains at best uncertain.
This is the case of two Italian monuments of great value for
which, after years of investigations, the causes of their
instability still have not been found and for which there are only
mere hypotheses: the Basilica of St. Angelo in Formis and the
Pienza Cathedral.
St. Angelo in Formis
St. Angelo in Formis is a Benedictine basilica near Capua which
rises on the slopes of a rock hill (Fig. 12); it was built in the 6th
century A.D. on the ruins of a Roman temple whose origins date
back to the 5th century B.C (Cammarota, 2013). The basilica,
which has three naves, presents traces of the changes it
underwent in time. In particular the bell tower and the portico
probably collapsed and were rebuilt in the 13th century. The
foundations of the apse, most of the external walls and the
pillars of the naves are rather shallow and rest on a fractured
dolomite mass, whereas the foundations of the facade, the
portico and a small proportion of the side walls rest on debris
deposits and backfill.
The geology of the area is complex because the dolomite
mass overlies more recent Oligocene and Myocene deposits and
there are major fractures of tectonic origin (Fig. 13). There is
knowledge of relevant repair and consolidation measures
adopted in 1732 and in 1930 after seismic damages. Of the more
recent earthquakes of 1962, 1970 and 1980, only the last one
caused some slight damages. From the end of the 1960s some
cracks of static origin appeared in the walls of the naves lying
over the pillars and with their slow progression they have
caused quite some alarm and have required underpinning props.
Figure 12. The Benedictine Basilica of St. Angelo in Formis.
a)
b)
Figure 13. St Angelo in Formis. a) The main fissures; b) Geologic
section of the foundation soil (Cammarota et al. 2013).
The geological and geotechnical investigations performed so
far in different stages have not helped to identify the causes of
the settlements of the foundation soil. A first hypothesis
attributed the instability to the mining activities carried out
using explosives in a nearby quarry, but even after the mining
