自平衡试桩法在渡槽桩基础承载性能检测中的应用

Application of self-balanced method in detection of bearing capacity of pile foundation for conduit (of south-to-north water transfer project)

南水北调中线总干渠与青兰高速连接线交叉工程中,采用渡槽跨越青兰高速连接线。渡槽槽身为分离式扶壁梯形渡槽,渡槽下部支承结构由实体板墩、承台和桩基础三部分组成。本文结合该工程2根试桩自平衡试验结果,通过分析单桩极限承载力、桩身轴力、土层摩阻力等技术参数,对桩基础承载特性进行了研究,并探讨了施工工艺对桩基础承载性能的影响。试验结果表明桩基承载力均高于设计要求,其中干挖作业法因沉渣较少,桩基承载力相对得到了提高,在类似工程中推荐采用。

Aqueduct crossing was applied in the transposition project,which connects the main canal in the centerline of the South Water to North project and the Qinglan expressway. The aqueduct itself takes the separated counterfort trapezoid structure and the lower supporting structure is made of slab pier, bearing platform and pile foundation. The paper takes reference from the self-balanced experiment result of the two trail piles and conducted study on the bearing performance of the pile foundation with the help of some technical parameters,like the ultimate bearing capacity of single pile,axial force of the pile and friction force of the soil layer. At the same time,it discusses the influence of the technology process on the bearing performance of the pile foundation. The results indicates that the bearing performance exceeds the designing requirements and dry digging operation method should be recommended in future construction,as the limited sediment greatly improved the bearing performance.