在美国,有着成万公里陡削的堤岸和斜坡,其坡度在30°到70°之间,其中大部分土地在人口集中的地方或其附近。这些陡坡一般有100米之高,甚至还高一些,其大部处于自然的稳定状态,或经相当简易的工程处理后可以稳定。尽管这样,由于下沉滑落,用传统的方式来开发通道和住宅是困难而昂贵的,有时甚至是危险的。其结果是过密的房屋排满了坡顶和散播在坡底平地上,而斜坡还是不能利用。这样,最好的农用土地最先被占用,而实际上,工业场地和自然资源比如砾石厂和石料场则由于住宅的拥挤而无处立身。 In the United States, there are tens of thousands of kilometers of steep embankments and slopes with slopes between 30° and 70°, most of which are in or near densely populated areas. These steep slopes are generally 100 meters high or even higher, and most of them are in a stable state of nature, or they can be stabilized after being handled by a relatively simple project. Despite this, due to sinking down, it is difficult and expensive to develop channels and houses in the traditional way, sometimes even dangerous. As a result, dense houses are filled with slopes and spread on flat ground, while slopes cannot be used. In this way, the best agricultural land was first occupied, and in fact, industrial sites and natural resources such as gravel and stone yards have nowhere to live due to the crowded houses.