概述1 1　夯扩桩发展史传统的普通直径 (ｄ 5 0 0ｍｍ)沉管灌注桩由于单桩竖向承载力不够大 ,一般只能作为多层建筑及 10层左右高层建筑的基础。为适应 11～ 30层高层建筑桩基础单桩承载力的要求 ,国内外在研制开发大直径沉管灌注桩的同时 ,也研制开发出一系列沉管扩底灌注 Overview 1 1 Development history of cast-in-place piles Traditional ordinary diameter (d500mm) cast-in-place bored piles cannot be used as foundations for multi-storey buildings and high-rise buildings of about 10 stories because the vertical bearing capacity of a single pile is not large enough. In order to meet the requirements for the bearing capacity of 11- to 30-story high-rise building pile foundations, a series of immersed pipes have been developed at home and abroad while developing large-diameter immersed pipe piles.