Effects of particle breakage and stress reversal on the behaviour of sand around displacement piles
Effects of particle breakage and stress reversal on the behaviour of sand around displacement piles
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DOI：
10.1680/jgeot.17.p.117
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发表时间：
2018-06-01
期刊：
影响因子：
5.8
通讯作者：
Moinet, W. W.
中科院分区：
文献类型：
--
作者：
Altuhafi, F. N.;Jardine, R. J.;Moinet, W. W.
在枫丹白露 NE34 砂上进行的三轴应力路径试验中，模拟了在中密砂中安装和加载期间作用在位移桩尖端和桩身附近土体中的应力。在涉及相同砂子的校准室模型桩试验中记录的非常高的法向应力和剪切应力首先在高压三轴试验中再现，从而显着改变了砂子的物理特性。然后在相同实验的第二个较低应力阶段检查突变砂的行为，证明砂的机械行为发生了重要变化，包括抗剪角度的显着增加以及砂的临界状态线在 e-log p' 平面中的重新定位。图像分析证实了沙粒微观特征的变化。颗粒尺寸分布发生改变，颗粒表面粗糙度显着增加，而颗粒球形度仅受到轻微影响。在三轴实验室测试后检查的样本的颗粒特征与从校准室模型桩的轴周围取样的样本之间注意到类似的表面粗糙度变化。
The stresses acting in the soil mass adjacent to the tips and shafts of displacement piles during installation and loading in medium-dense sand have been simulated in triaxial stress path tests on Fontainebleau NE34 sand. The very high normal and shear stresses recorded in calibration chamber model pile tests involving the same sand were first reproduced in high-pressure triaxial tests, so changing the sand's physical properties markedly. The behaviour of the mutated sand was then examined in second, lower stress, stages of the same experiments, demonstrating important changes in the sand's mechanical behaviour, including a significant increase in the angle of shearing resistance and a relocation of the sand's critical state line in the e-log p' plane. Image analysis confirmed changes in the sand particles' micro-characteristics. The particles' size distributions altered and grain surface roughness increased markedly, while particle sphericity was only mildly affected. Similar surface roughness changes were noted between the particulate characteristics of specimens examined after the triaxial laboratory tests and those sampled from around the shafts of the calibration chamber model piles.