无锡大直径超长钻孔灌注桩承载性状试验研究  

Experimental study of the bearing properties of large-diameter and super-long bored pile in Wuxi

作　　者：张瑞坤[1] 石名磊[1] 倪富健[1] 王晋[1] 

机构地区：[1]东南大学交通学院,南京210096

出　　处：《东南大学学报（自然科学版）》2012年第6期1194-1200,共7页Journal of Southeast University：Natural Science Edition

基　　金：建设部研究开发资助项目(2008-K2-12)

摘　　要：基于无锡地铁高架桥试桩工程中4根大直径超长钻孔灌注桩的现场静荷载试验和桩身应力测试试验,结合同一地区12根同类型桩的试验成果,研究了无锡地区大直径超长钻孔灌注桩竖向荷载下的侧、端阻力发挥特点和荷载传递规律.研究表明:不同的大直径超长钻孔灌注桩施工工艺会造成桩底沉渣厚度差异,宏观表现为Q-s曲线形态呈陡降型或缓变型.大直径超长钻孔灌注桩单桩受竖向荷载,侧摩阻力从上到下逐步发挥,侧、端阻力非同步发挥且相互影响.不同埋深条件下,物理性质相同土层提供的侧摩阻力实测极限值与规范推荐值差异较大,说明侧摩阻力深度效应显著,且浅层黏土易发生软化效应.发挥侧摩阻力极限值所需桩土相对位移为4～7mm.该结论可指导该地区同类工程的设计和施工.The static load test and the pile stress test of four large-diameter and super-long bored piles in Wuxi Subway project were carried out.The characteristics of the pile＇s skin friction resistance,the tip resistance and the load transmission law were analyzed based on the test data together with the relevant test results from other 12 piles.The results show that the different bottom sediment thickness caused by different construction technologies lead to the steep drop or slow change of the Q-s curve shape.The skin friction resistance of the large-diameter and super-long bored piles exerts gradually from top to bottom.The skin friction and tip resistance do not work simultaneously and have mutual influence on each other.There are significant differences in side friction resistance between the measured values and the recommended values,which indicates that the depth effect of side friction resistance and the softening effect of the shallow cohesive soil are both notable.The value of pile-soil displacement boundary under ultimate load is 4 to 7 mm.The conclusions are useful for other similar engineering practices.

关 键 词：大直径超长钻孔灌注桩 荷载传递 静载试验 桩侧阻力 桩端阻力 

分 类 号：TU473[建筑科学—结构工程]