Behaviour of jacked and driven piles in sandy soil
Behaviour of jacked and driven piles in sandy soil
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DOI：
10.1680/geot.2006.56.4.245
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发表时间：
2006-05-01
期刊：
影响因子：
5.8
通讯作者：
Yu, F.
中科院分区：
文献类型：
--
作者：
Yang, J.;Tham, L. G.;Yu, F.
作为传统动力桩安装方法的替代方案，顶桩是一种环境友好的技术，将得到越来越广泛的接受。与打入桩相比，静压桩的性能引起了人们的广泛关注。本文描述了一项全面的现场研究，旨在调查静压h型桩与打桩h型桩之间的差异和相似之处。测量桩的长度从32米到55米不等，设计承载力可达3540千牛，安装在性质接近粉砂的残余土中。荷载试验结果表明，一般情况下，静压桩的桩身阻力比打入桩的桩身阻力更硬、更强，但桩身阻力比打入桩的桩身阻力弱。在荷载水平为设计能力的两倍时，静压桩基底承担的桩头荷载百分比从2%到10%不等，平均值为6%；对于打入桩，这一比例从6%到61%不等，平均值为38%。后算的桩身摩擦系数beta值在0.25-0.6之间，对于顶桩和打入桩均是如此。同时还观察到，h型桩的极限桩身摩阻力与标准贯入试验平均N值（N / bar）之间存在一定的相关性，表明桩身摩阻力可取为1.5 (N) / bar ~ 2 (N) / bar （kPa）。
As an alternative to conventional dynamic pile installation methods, pile jacking is an environmentally friendly technique that could become more widely accepted. Great concern has arisen over the performance of jacked piles as compared with that of driven piles. This paper describes a comprehensive field study that was aimed at investigating the differences and similarities between the behaviour of jacked H-piles and that of driven H-piles. The instrumented piles, varying in length from 32 to 55 m and having a design capacity of up to 3540 kN, were installed in residual soils whose properties are close to silty sands. The load test results indicate that the shaft resistance of jacked piles is generally stiffer and stronger than that of driven piles, but the base resistance of jacked piles is weaker than that of driven piles. At a load level of twice the design capacity, the percentage of pile head load carried by base varies from 2% to 10% for jacked piles, with a mean value of 6%; for driven piles the percentage varies from 6% to 61% with a mean value of 38%. The back-calculated values of the shaft friction coefficient, beta, were found to be in a range of 0.25-0.6 for both jacked and driven piles. A correlation was also observed between the ultimate shaft friction and the mean standard penetration test N value ((N) over bar), which suggests that the shaft friction can be taken as 1.5 (N) over bar to 2 (N) over bar (kPa) for both jacked and driven H-piles.