290420874

Milan

Milan is a quite modern city, yet it includes mo numents of great artistic and historical value. In the period between 1950 and 1970 the city has been subject to a light subsidence, which didn’t cause any inconvenient to recent constructions. On the contrary the Cathedral, the most famous monument in Milan, underwent serious consequen-ces.

In fact, the differential settlements caused by the subsidence, although smali, appeared unacoep table by the bold architectural design of the building.

The diagnosis was fairly simple and the cause of the subsidence has been easily removed by gradu ally closing the pumping wells in a wide area.

I will then omit the specific aspects of geotech nical engineering and I'd rather mention some a spects of the work in progress to reinforce the structures.

Fig. 5

During the six centuries past from the foundation of the Cathedral,smali superficial cracks occasi onally occurred in the columns and vaults.Owing to the subsidence,this deterioration of the monu ment remarkably increased,so that the risk of a sudden collapse was feared.

Therefore it was necessary to transfer the loads transmitted by the domes and the vaults directly to the foundations.In this way it was possible tc substantially reduce the stress-field in the co lumns,whose materiał had seriously weakened (Fig. 5) .

Instead of using traditional shoring methods,the Architect of the Cathedral followed a new course.

He designed,tested on models and then carried out different types of reinforcements to be super imposed on the original compromised structures (Fig.6).

With the protection provided by these support sy

Fig. 6

stems,the Architect will now turn towards the exe cution of an inverse operation.

He will gradually eliminate the superimposed rein forcements,while proceeding to improve and reccn struct the materiał of the original structures.

I cited the problem of the temporary support of the monuments,sińce it happenes sometimes that the overlying structures are in good static con-ditions and the work has to be carried out on the foundations or on the subsoil.However the monument requires temporary support.

This could be the case of the Leaning Tower of Pisa.

References

COLLESELLI F.,DONELLI P. - Le "Fondamente" di

nezia: evoluzione storica, cause di disse-sto e metod i di risanamento.XIV Convegno Na zionale di Geotecnica, Firenze (1980)

COLOMBO P. - Probierni relativi alla difesa del-la citta di Venezia. RIG (1972)

COMUNE DI COMO - Relazione di Sintesi della Com missione per lo Studio dei Fenomeni di Sub sidenza. Como,(1980)

CROCE A. - Subsidence et Mecanique des Sols dans la Vall6e du Po. I.T.Bat.Trav.Publ., Paris (1975)

CROCE A. - II Campanile di Pisa. Atti Convegno Subsidenza, Pisa (1978)

CROCE A. - Relazione Generale, XIV Convegno Na-zionale di Geotecnica, Firenze (1980)

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