1. The leaning tower of Pisa is inclined because of the particularity of the soil layer under its foundation. Below the Leaning Tower of Pisa are several layers of soil with different materials, and all kinds of soft silt and extremely soft clay deposits are alternately formed, while at a depth of about one meter, it is a groundwater layer.

The leaning tower of Pisa did not collapse. First of all, it is because its body is stronger. Second, the tilt angle is still within the safe range, and the center of gravity is still not beyond the geometric edge.

2. At present, the accepted remedy is the foundation stress relief method, but I think this method is flawed: from the overall structure, this method is very correct. However, from a microscopic point of view, this method is bound to have a certain impact on the tower structure; And it must be carried out for a long time, otherwise it will be "overcorrected";

Since only one picture can be uploaded, the two answers are merged: