Why… the pisa tower is that leaning?

It is for his famous leaning tower that Italian town of Pisa is most famous. Far from being a creation of an extravagant architect, she testifies to approximate unstable foundations in land.


Fruit of luck constructional flaw, poor quality of the floor? What can do to put the Leaning tower in this way? Today's one of the Italian symbols into the most tourists even if his characteristic is now well.

The Leaning tower is on the Place of the Miracles in the middle of the city. © Picture.
A penchant for years
It is a bell-tower, a high tower and right, whose role is to shelter the bells of the cathedral who copes. Put it in heart œ of Pisa, the construction is in 1173 started and does not last less than two centuries.
Today we know because he is very bent, but that is nothing new. Yes, he was only five straight years. By 1178, and only three of the seven floors are built, it is starting to be inclined. Is that the rest of work: the last four floors are built diagonally to compensate for the ramp. The end of construction and is delayed, but in 1372, the building is finished.
So already, in the 14th century, the banister is visible and the “tower” is stuck in the ground. Over the years it is not tidy, on the contrary. In the middle of the 14th century, the slope of the tower is estimated about 1,47° in 1993 and 5,63° at: that means the summit is isolated from more than 5 feet from its axis of origin.
Several possibilities
It is not difficult to: he leans. However, it is difficult to say why. First guess: it is built in a alluvial plain so the causes are sedimentary. Too hot, too sandy soil or argillaceous movable too because that would let the tower deep and bow to you. Very good. By 1995, earth is treated by a cryogenic systems cooling aiming at him to stop the race to the land of the tower. The results are not satisfactory, the tower leans more and more fast.
Second guess: then you look more closely at the level of the foundation and in 1998 you decide to reinforce them with a steel structure and pillars. Today the tower is stable and bent less than in the past. So if the Leaning tower is leaning, partly because of his foundation: they are unsuited to on the land on which they are built.