The Leaning Tower of Pisa Gareth Jones And Ben Fenton

History of Construction 1173 – 1178 Tower completed to the 4th storey 1272 - 1278 Tower completed to the 7th storey 1360 – 1370 Bell Tower completed 1838 Walkway around foundations excavated

Geology of Pisa 300m of sediments over the bedrock beneath Pisa Layer A :10m of fairly dense river silts Layer B : 30m of marine clay – ‘Pancone Clay’ Layer C : 260m of dense sand. Water table 1 – 2m below surface

Tilt Stopping Solutions Curving Construction Counter Weight Grouting - Masonry Grouting - Foundations Tying Masonry Destructive or detrimental to appearance Therefore temporary solutions

Failed Attempts 1995 - Anchor north side to stronger sand beneath clay Concrete ring around foundations – below water table Excavation in 1838 caused inrush of water 1995 – injected liquid nitrogen to freeze groundwater Compressed clay on south side causing greater tilt

Permanent Solution Stabilised with 2 steel cables Extracted soil from North of Tower

Permanent Solution

Results Rotation towards North South Face Rising North Face Sinking

The Future Scenario 1 : Tower remains stable for a period, then rotates southwards at a reduced rate (300 years until intervention). Scenario 2 : Rotation of the Tower will cease.

The End Thank-you