Foundation Performance of Tower of Pisa

by James K. Mitchell, (F.ASCE), Prof. of Civ. Engrg.; Univ. of California, Berkeley, Calif.,
T. William Lambe, (F.ASCE), Prof. of Civ. Engrg.; Massachusetts Inst. of Tech., Cambridge, Mass.,
Vitoon Vivatrat, Grad. Research Asst.; Massachusetts Inst. of Tech., Cambridge, Mass.,

Serial Information: Journal of the Geotechnical Engineering Division, 1977, Vol. 103, Issue 3, Pg. 227-249

Document Type: Journal Paper


A number of readily available bearing capacity and settlement analysis techniques, in conjunction with the results of recent comprehensive soil studies, have been used to study the performance of the Leaning Tower of Pisa. There is little likelihood that the bearing capacity of any of the foundation soils was exceeded at any state during the life of the Tower. The total settlement of the Tower results from: (1)Immediate compression of the sands in a 7-m thick zone underlying the base of the Tower; (2)immediate compression of a 30-m thick clay layer underlying the sands; (3)consolidation of the clay layer; and (4)secondary compression of the layer. Calculated magnitudes and rates of settlements agree well with measured values. The underlying compressible layers have uniform thicknesses; therefore, geometric factors did not likely cause the Tower lean. Available soil data do indicate, however, that the sand layer is more compressible on the south side of the Tower than on the north. This variation in compressibility is, therefore, a possible cause of the lean.

Subject Headings: Soil compression | Soil settlement | High-rise buildings | Layered soils | Foundations | Load bearing capacity | Soil analysis | Clays

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