软土地区超长单桩承载特性的现场试验研究  

Bearing behaviors of super-long single pile in soft soil areas

作　　者：张骞[1] 李术才[1] 张乾青[1,2] 李利平[1] 周宗青[1] 

机构地区：[1]山东大学岩土与结构工程研究中心,山东济南250061 [2]中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏徐州221116

出　　处：《岩土工程学报》2013年第S2期1066-1070,共5页Chinese Journal of Geotechnical Engineering

基　　金：中国矿业大学深部岩土力学与地下工程国家重点实验室开放基金项目(SKLGDUEK1210);中国博士后科学基金面上项目(2012M521339);山东大学自主创新基金项目(2012GN012)

摘　　要：软土地区超长钻孔灌注桩现场静载试验表明,浆液上返作用对桩侧泥皮的固化作用和桩端浆液对桩端沉渣和持力层的压密固化作用使得后注浆桩的承载能力得以提高。使用荷载下,桩身压缩占桩顶沉降的90%以上,最大试验荷载时桩顶沉降的70%来自桩身压缩。在对超长桩进行设计时,不能忽视桩身压缩对桩顶沉降的影响。超长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未完全发挥。传统的超长桩承载力计算方法和其实际承载能力会有一定误差。The static load test results of super-long bored piles in soft soil areas show that the curing effect of slurry on mud cake around pile shaft and the compaction and curing effect of slurry on the sediment and bearing layer can improve the bearing capacity of single pile. Under the working load, the compression of pile shaft accounts for more than 90% of pile top settlement, and the percentage of super-long pile top settlement caused by the compression of pile shaft is over 70% under the maximum load. Therefore, the influence of pile shaft compression on the pile head settlement should not be ignored in the design of super-long piles. Moreover, it can be concluded that the skin friction softening occurs in the upper soil layers of the super-long piles, whereas the skin friction in the deeper soil layers can not be fully mobilized. The traditional methods for the bearing capacity calculation of supper-long piles will have a certain error in the actual bearing capacity.

关 键 词：钻孔灌注桩 注浆 桩身轴力 桩土相对位移 桩侧摩阻力 

分 类 号：TU473.1[建筑科学—结构工程]