我国目前采用较多的钢筋混凝土桩,是靠桩周摩阻力与桩底端承力共同作用来传递荷载的。要提高桩的摩阻力,只有增大桩径或提高桩的比表面积,但这是不经济的。人们转而对提高桩的端承力上进行了研究,出现了扩底桩、夯扩桩等改良桩。近几年,又发展有新型挤压分支桩,从而有效地提高了单桩承载力。 挤压分支桩分钻孔挤压分支桩和振动沉管挤压分支桩两种形式。钻孔挤压 At present, more reinforced concrete piles are used in our country, and the loads are transmitted by the frictional resistance of the pile and the bearing capacity of the bottom of the pile. To increase the friction resistance of the pile, only increase the pile diameter or increase the specific surface area of ​​the pile, but this is uneconomical. People turned to improve the end bearing capacity of the pile on the study, there have been expanded piles, rammed piles and other improved piles. In recent years, a new type of extruded branch pile has been developed, which effectively improves the bearing capacity of single pile. Extruded branch of the sub-hole drilling bored squeeze branch pile and vibratory tube extrusion bifurcation two forms. Drill extrusion