钢管桩逆作复合基础竖向承载性能试验研究  

EXPERIMENTAL STUDY ON BEARING PERFORMANCE OF STEEL PIPE PILE COMPOSITE FOUNDATION CONSTRUCTED BY TOP-DOWN METHOD UNDER VERTICAL LOADS

作　　者：周儒夏[1,2] 龚维明[1] 杨乐[1,3] 柏平 

机构地区：[1]东南大学土木工程学院,南京210096 [2]南通市公路管理处,江苏南通226001 [3]中冶华天工程技术有限公司,南京210096

出　　处：《工业建筑》2012年第4期89-94,共6页Industrial Construction

基　　金：西南交通建设科技项目(2009318494041)

摘　　要：为了研究砂性土中钢管桩复合基础的承载特性,设计了模型桩系列试验。结果表明:对于单桩复合基础,封桩前阶段的荷载全部直接由承台底砂土承担,封桩后阶段桩体达到极限承载力之前,桩体分担的荷载占荷载增量的73.5%～92%,当桩的承载能力达到极限后,随着荷载的继续增加,桩分担的荷载比例较之前衰减明显,而土体分担的荷载比例增加。钢管桩八桩复合基础中,桩身轴力在桩身上部的衰减梯度明显小于中下部,角桩衰减速率最大,边桩次之;桩身摩阻力自上而下逐渐发挥,桩顶以下1.55 m处摩阻力达到最大;每级荷载作用下,角桩的侧阻力大于边桩。钢管桩群桩复合基础的竖向承载力远大于相对应的高承台群桩承载力。Model tests were designed to investigate the bearing capacity properties of composite steel pipe pile foundations in sandy soil.Results indicated that：To a single pile composite foundation,the load was totally carried by ground under the cap before sealing piles.Then,after sealing,the pile started to work and the pile-soil load share ratios were between 73.5%~92% before reaching ultimate bearing capacity.As vertical load increased continually to the capacity limit,the ratio reduced obviously.To a composite foundation with 8 steel pipe piles was tested,the attenuation gradient of axial load was larger in the middle and lower parts rather than the upper part during axial load transfer.The rates of the corner piles were biggest,then the side piles.The side frictional resistances developed gradually from the top to the bottom and the maximum value reached at the distance of 1.55 m below the top.At every load step,the resistances of the corner piles were greater than that of side piles.Moreover,the ultimate bearing capacity of the steel pipe pile composite foundation was significantly higher than that of the high-rise cap pile group foundation.

关 键 词：钢管桩 逆作法 承台 荷载分担 沉降 

分 类 号：TU473.1[建筑科学—结构工程]