Three million people visit Pisa each year. Why do they come to this town in Italy? To see a tower. The crazy tower leans! It is known as the Leaning Tower of Pisa.
The tower looks as if it might fall at any time. In fact, some visitors stop at the tower just long enough to take a picture. Then they hurry away. Other visitors climb the 296 steps to the top—and come down, feeling like heroes.
Engineers say that the visitors are safe—at least for a while. But the tower does lean. It slants2 14 feet 6 inches at the present time. The tower has been leaning for more than 800 years. And every year it leans a tiny bit more. If this keeps on, the tower will fall.
You may wonder what makes the tower lean. If you look at the picture, you will see that one side of the tower is deeper in the earth than the other. The foundation on which the tower rests has sunk3 into the soil on the leaning side. Why has this happened?
Pisa's tower weighs 14,500 tons. The soil of the tower is a mixture of clay and water. A heavy tower built on soil like this must have a very strong foundation. The Leaning Tower's foundation is just not deep enough and wide enough for the tower above it.
Can anything be done about the tower?
Yes, Italian engineers have several plans. They don't want to make the tower straight—just keep it from leaning any further. So all the plans call for a new foundation that won't sink.
The Italian engineers are searching for the best plan that will cost a lot of money. They are trying to get the money from the Italian government. But many Italians refuse to believe that the old tower is in danger. “It leans and leans and leans,” they said. “But it will never fall down.”
The engineers want to make sure that it won't.
每年有三百万人前往比萨参观。人们为何纷纷来到这个意大利小城呢？为的是看一座塔，这座不可思议的塔倾斜了，这就是众所周知的“比萨斜塔”。
这座塔看上去随时都会倒塌。事实上，一些游客在塔下一拍完照就匆匆离开。另外一些游客则爬上296级台阶到达塔顶，然后再下来，俨然英雄一个。
工程师们说游客们没有危险——至少在一段时间内。但是塔身的确倾斜了。目前已经倾斜了14英尺6英寸。它连续倾斜了800多年！每年都倾斜那么一丁点儿，照这样下去，塔终究会倒塌。
你可能会好奇：是什么引起了塔的倾斜？如果你看一看工程图，就会发现塔基的一边比另一边陷得要深。支撑塔身的塔基在倾斜的那一边沉陷进了泥土。 为什么会这样呢？
比萨斜塔重14,500吨，而塔基土壤则是粘土和水的混合物。建在这种土壤上的重塔必须有非常牢固的地基。而斜塔的地基既不够深，又不够宽，难以支撑塔身的重量。
那有无挽救措施呢？
有，意大利工程师们拟定了几种方案。他们不想把塔竖直——只想防止它进一步倾斜。因此所有的方案都要求新的地基不会下沉。
意大利工程师正在寻找最佳方案，这个方案耗资巨大。他们试图从意大利政府手里获取资金。但是许多意大利人不相信这座古塔处于危险之中。“塔在不断地倾斜、倾斜”，他们说，“但它永远不会倒下”。
工程师们就是想确保比萨斜塔不会倒塌。
1. Pisa n． 比萨（意大利中部一城市）
2． slant v．倾斜
3． sink v．下沉，倾斜