The shaft capacity of driven piles in clay increases with time even after installation-induced consolidation is completed. However, existing studies have shown that these gains in capacity are variable and cannot be predicted reliably. Projects such as those involving life extension of existing offshore platforms (which often involve increased platform loads) as well as those considering foundation re-use provide the motivation for this paper, which investigates the potential for model scale testing to replicate the ageing characteristic of shaft friction in a laboratory environment. The study employs a number of model piles installed in reconstituted, high plasticity Onsoy clay in laboratory pressure chambers. The first time tension load tests on these piles, performed over the period of 1 year after installation, are compared with a similar series of tests on full-scale driven piles in Onsoy, Norway. Good agreement between laboratory and field experiments is observed when allowance is made for the significantly longer consolidation periods of the full-scale piles. This finding implies that ageing effects of shaft friction in clay can be investigated over relatively short time periods using model piles in laboratory testing chambers.

中文翻译：

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基于实验室的方法来确定粘土中桩轴摩擦老化的研究

即使在安装诱导的固结完成后，粘土中打入桩的轴容量也会随着时间的推移而增加。然而，现有研究表明，这些容量增益是可变的，无法可靠预测。诸如涉及现有海上平台寿命延长（通常涉及增加平台载荷）的项目以及考虑基础再利用的项目为本文提供了动力，该论文研究了模型规模测试以复制轴老化特性的潜力实验室环境中的摩擦。该研究使用了许多模型桩，这些模型桩安装在实验室压力室中的重组高塑性 Onsoy 粘土中。在安装后的 1 年内对这些桩进行首次拉伸载荷测试，与在挪威 Onsoy 进行的全尺寸打入桩的类似系列测试进行了比较。当考虑到全尺寸桩的显着更长的固结期时，可以观察到实验室和现场实验之间的良好一致性。这一发现意味着可以在实验室测试室中使用模型桩在相对较短的时间内研究粘土中轴摩擦的老化效应。