粘性土层中PHZ方桩荷载检测数据异常分析  

Analysis of abnormal data of loading test on hollow square pile in clay

作　　者：赵飞涛 窦斌[1] 钱进中 肖斌 Zhao Feitao;Dou Bin;Qian Jinzhong;Xiao bin(China University of Geosciences(Wuhan),Wuhan 430074,China;Xiangyang Architectural Design Institute,Xiangyang 441000,China;Wuhan Jiancheng Engineering Technology Co.,Ltd.,Wuhan 430074,China)

机构地区：[1]中国地质大学(武汉),武汉430074 [2]襄阳市建筑设计院,湖北襄阳441000 [3]武汉建诚工程技术有限公司,武汉430074

出　　处：《工程勘察》2022年第10期37-42,共6页Geotechnical Investigation & Surveying

摘　　要：某项目在桩基载荷试验时发现,中等压缩性粘土层中施工的PHZ方桩出现了承载力大幅度低于压桩力的异常情况,且荷载—沉降曲线均为陡降型,具有典型的摩擦桩特征,试验最大荷载约等于经验参数计算的桩侧总极限摩阻力。对后续施工的PHZ方桩进行上浮观测发现,绝大多数桩均有不同程度的上浮,先施工桩上浮量要远超后施工桩,间距较密、桩长较长的3~#楼、4~#楼的桩最大和平均上浮量均超过地下室的桩,观测数据表明管桩承载力降低是由于桩体发生上浮导致的。根据沉桩过程中的桩土相互作用,结合上浮观测数据对预制桩的上浮原因进行了分析,明确了群桩挤土作用是桩体发生上浮的主要因素,据此提出复压、引孔等工程措施解决桩体上浮问题。During the pile load test of a project, it is found that the bearing capacity of PHZ square pile constructed in medium compressible clay is significantly lower than the pressing load, and the load settlement curve is a steep drop type, which conforms to the characteristics of typical friction pile. The maximum load of the test is approximately equal to the total ultimate friction resistance of pile side calculated by empirical parameters. The most piles are floated based on observation, and the floating amount of pile constructed before is much higher than that of pile constructed after. The maximum floating is located in the Building No.3 and No.4 where the pile is longer and the spacing is smaller, and the pile capacity is lower because of pile floating based on the observation data. According to the pile-soil interaction in the process of pile jacking and combined with the observation data of floating, the reasons for the floating of precast piles are analyzed. The pile floating is mainly caused by soil squeezing effect of pile groups. The engineering measures such as repeatedly jacking and pile hole pre-boring could be applied to solve the floating problem.

关 键 词：PHZ空心方桩 上浮 监测 挤土效应 

分 类 号：TU473.16[建筑科学—结构工程]