竖向高荷载作用下大直径超长钻孔灌注桩承载性能试验  

Experiment on bearing capacity of large-diameter and super-long bored pile under vertical heavy load

作　　者：桑伟锋 SANG Wei-feng(Henan Provincial Communications Planning Survey&Design Institute Co.,Ltd.,Zhengzhou 450052,China;Henan Jiaoyuan Engineering Testing Technology Ltd.,Zhengzhou 450052,China)

机构地区：[1]河南省交通规划设计研究院股份有限公司,郑州450052 [2]河南省交院工程检测科技有限公司,郑州450052

出　　处：《世界地质》2020年第1期127-134,共8页World Geology

基　　金：河南省交通运输厅科技项目(2016P38)。

摘　　要：通过机场—西华高速大直径超长钻孔灌注桩大吨位竖向单桩静载试验,分析了该地区大直径超长钻孔灌注桩的承载性状以及荷载传递机理。试验结果表明:试桩的Q-S曲线呈缓变型,桩端承载力占总荷载的比例均<10%,即均表现为摩擦桩特性;试桩的侧摩阻力自上而下逐步发挥,侧摩阻力和桩端阻力异步发挥且互相耦合;大直径超长钻孔灌注桩桩侧摩阻力的发挥与土层性质、土层埋深及桩顶荷载水平有关;在高荷载作用下桩侧上部土层摩阻力具有不同程度的软化现象,而中下部土层侧摩阻力具有不同程度的强化现象,甚至即使在最大加载情况下,桩身下部土层的侧摩阻力也并未完全发挥,因此在根据规范计算超长桩承载力时,不同深度土层的侧摩阻力应乘以相应不同的修正系数。The large tonnage static load tests on large-diameter and super-long bored piles of airport to Xihua expressway were carried out to investigate the bearing capacity and mechanism of load transfer.The results show that load carrying(Q-S)curves of the piles vary gradually.The piles tested have the characteristics of friction piles because the loads at the pile tips are less than 10%of the total bearing capacity of the piles.The lateral friction resistance of test pile is developed from top to bottom,and lateral friction resistance and end resistance are asynchronous and coupling.The lateral friction resistance of large-diameter and super-long bored piles is related to the properties of soil layer,the buried depth of soil layer and the load level of pile top.Under heavy load the shaft resistance of piles has a slight weakened and enhanced effect in the upper and lower soils,respectively.Even in the condition of highest heavy load,the lateral friction in lower soils didn t play well,which means that the shaft resistance in different soil layers and the tip resistance should multiply different modification coefficients in estimating the bearing capacity of super-long piles.

关 键 词：大直径超长灌注桩 高荷载 承载性能 侧摩阻力 软化 

分 类 号：P634.5[天文地球—地质矿产勘探]