78
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
Main events in the Cathedral history (Fig. 18)
1458, Enea Silvio Piccolomini is elected pope (Pius II) and begins to
rebuild his home town.
1459, The construction of the Cathedral is initiated by Bernardo
Rossellino. Some problems arise in the apse foundation.
1462, At the end of the works some fissures appear close to the first
choir chapel. Their openings increase towards the vaults. (a)
1462, Aug. 29, Solemn opening of the Cathedral.
1490, The apse begins to settle.
1500, The settlement of the apse reaches about 0.3 m.
1503, A tunnel is built to drain water from under the crypt.
1508, Two buttress piers are built against the apse to sustain it.(b)
1514, A wall is built around the apse. The settlement reaches 0.45 m
1545, Nov. 25, An earthquake (?) causes a large settlement of the apse
and the collapse of the belfry; a crack appears along the natural
scarp, SW of the town. (c)
1570, Repair works of the earthquake damages are completed. The
collapsed vaults of the transept are substituted by false vaults
1596, The crypt arches and the external walls are streightened.
1604, A. Sandrini, architect, states that the damages are due to the
slope movement, so that underpinning the apse is useless. (d)
1650 - 1760, Repeated repair works. The apse is more than 25 cm out
of the plumb line.
1750 - 1770, A proposal of demolishing the apse and shortening the
church is considered, but happily not carried out.
1888 - 1895, Collapsing vaults are replaced by false works. The
pillars are connected by steel tendons. The apse has settled 0.85 m
and has increased its detachment from the nave. (e)
1911 - 1925, Underpinning of the apse with masonry pillars, which
bypass the sandstone layer to reach the marly clay. (f)
1926 - 1929, Various repair works are carried on, the apse walls are
strengthened. The transept is underpinned.
1930 - 1933, The apse and crypt vaults are rebuilt. (g)
1958 - 1962, Underpinning of nave and aisle pillars with root piles. A
hydraulic diaphragm is built around the front. (h)
a)
b)
c
)
d)
e
)
f)
