1. The Leaning Tower of Pisa
Gareth Jones
And
Ben Fenton

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

3. 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

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

5. 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

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

7. Permanent Solution

8. Results
Rotation towards North
South Face Rising
North Face Sinking

9. 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.

10. The End
Thank-you