The Leaning Tower of Pisa - a suggested remedial measure : 4F, 5R. Ground Engng, V9, N1, Jan. 1976, P38–40

Abstract

The structure of the soil at the site and the tilt of the tower are described and explained. Remedial measures are suggested which are directed at the causes of the inclined position of the tower i.e. the compression of a 30 m thick thick layer of clay. It is suggested that compressing the clay layer with an external load on the side of the tower which is not leaning be carried out by degrees. The method is reversible. Close to the tower, but without touching it, an assymmetrical load would be applied approximately 9 m above the clay layer over the almost incompressible sand layer. A distribution of stress on the surface of the clay is thus attained which is superimposed on the existing stress to such an extent that the resulting stress distribution on the surface of the clay is more even and less eccentric. This corrective process can be started by first regulating the load, by controlling pore water pressure till the desired results are exactly estimated. The process may be accelerated by using an excess load. Details of the method are described, and its advantages are noted.