沉管灌注桩是我国应用时间较早、用量最大的极型之一，它早在本世纪3O年代即在上海开始应用，自70年代后陆续在东南沿海各省及华中、华北、东北各地大量推广，成为主要适合多层建筑的一种经济桩型。估计近20年来用沉管灌注桩建成的各类建筑物的建筑面积已达到数亿m‘，各地的此 The immersed cast-in-place bored pile is one of the earliest and most used polar types in China. It began to be applied in Shanghai in the 30s of this century, and has been widely promoted in the southeastern coastal provinces and in Central, North and Northeast China since the 1970s. Becomes an economic pile type that is mainly suitable for multi-story buildings. It is estimated that the building area of ​​various types of buildings built with immersed cast-in-place piles in recent 20 years has reached several hundred million meters.