桩的施工方法对桩基沉降的影响

Effects of Pile Installation on Settlement of Groups

通过对上海饱和软粘土中１７ 座钻孔桩基和１８ 座打入桩基的实测沉降资料对比，说明在荷载、地层剖面、持力层、桩长和桩基几何尺寸等都非常接近的条件下钻孔桩基的沉降小于打入桩基，揭示桩施工方法对桩基沉降的影响．根据桩施工引起的柱负摩阻力概念对两类桩基沉降差异的机制作了分析，并用此概念进一步说明影响打入桩基沉降的复杂性．

Observation data of 17 bored pile groups and 18 driven pile groups in soft soil regions of Shanghai indicate that settlement of driven pile group is greater than that of bored pile group when the conditions for two types of group in total load, soil situation around pile, bearing stratum, pile length and pile number are about the same. The data show the effects of pile installation on group settlement. Based on concept of negative friction induced by pile installation, settlement mechanism for two types of group and complication of negative friction for driven pile group are discussed.