钻孔灌注桩是用钻孔机具在地基中钻成一个圆孔,然后在孔中安装钢筋骨架并灌注混凝土所建成的一种基桩。国外资料这种施工方法基本上分三类。第一类是用打桩方法,把带有密闭管靴的钢套管打入土中,灌注混凝土时,逐渐拔出钢套管(管靴留在土中)。第二类是用冲击、回转或旋转式钻头等在钢套管中钻进,用抓斗出土并施力使钢套管逐渐下沉,到达设计标高后,在钢套管中灌注混凝土并逐渐拔出钢套管。第三类不用钢套管,只用各种钻头或射水直接 Bored piles are drilled into the foundation with a drilling tool into a round hole, and then install the steel skeleton in the hole and perfusion of a pile of concrete built. Foreign information This construction method is basically divided into three categories. The first category is the use of piling method, the steel pipe with a closed tube boots into the soil, pouring concrete, the gradual withdrawal of steel casing (pipe shoes left in the soil). The second category is the use of impact, rotary or rotary drill bit in the steel casing drilling, unearthed with grabs and force the steel casing gradually sinking to reach the design elevation, the concrete poured into the steel casing and gradually Pull out the steel sleeve. The third category without steel casing, only a variety of drill or water directly