【摘要】 挤土型桩的挤土效应一直是工程界研究和关注的热点问题之一。结合南京长江四桥北接线段现浇X形桩软基处理工程,首次开展现浇X形混凝土桩(简称X形桩)沉桩过程现场试验,测得不同X形横截面方向、不同距离及深度处的水平位移、侧向土压力以及孔隙水压力的分布规律,研究X形桩挤土效应规律。研究结果表明,最大水平位移发生在桩顶,距离5倍等效桩径处的土体水平位移可以忽略不计;随着桩中心距的增加,挤土压力和孔隙水压力逐渐减小,并且尖角方向的挤土压力大于凹弧方向的挤土压力。现场试验数据为X形桩的布置形式以及桩间距的选择提供有力的设计参考依据。更多还原

【Abstract】 Squeezing effects of different piles are hot issues and important problems in engineering design and constructions.Based on the Fourth Yangtze River Bridge.s north-line soft soil treatment engineering at Nanjing,the squeezing effects of X-section cast-in-place concrete pile(referred to as XCC pile) were studied.The influence of pile construction on pore water pressure changes,earth pressure and lateral displacement are observed by pre-laying piezometers,earth pressure cells and inclinometers,respectively.Instruments are embedded at different directions and different depths.Through analyzing the data from field tests,the squeezing effects of XCC pile are obtained.The results show that the maximum horizontal displacement occurs at the top of the piles;and these displacements can be neglected when the distance exceeds five times of equivalent pile diameter.It is also shown that crowded soil pressure and pore-water pressure decreased with the increasing of center distance;besides,pressure of sharp corner is larger than that of concavity.The data from field tests provide other engineers with reliable evidences.更多还原