Scour effects on the response of laterally loaded piles considering stress history of sand
Scour effects on the response of laterally loaded piles considering stress history of sand
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DOI：
10.1016/j.compgeo.2010.08.009
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发表时间：
2010-11
影响因子：
5.3
通讯作者：
Cheng Lin;C. Bennett;Jie Han;R. Parsons
中科院分区：
文献类型：
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作者：
Cheng Lin;C. Bennett;Jie Han;R. Parsons
冲刷是指桥梁或海上平台桩基周围土壤的移动，导致基础在横向或垂直方向上的承载力降低。分析受冲刷影响的桩基的常用方法是在保持剩余土层性质不变的情况下，去除冲刷土层。然而，这种方法忽略了这样一个事实，即剩余的土壤经历不同的应力历史之前和之后冲刷，可以预期改变剩余土壤的属性。因此，提供给桩基础的剩余土壤的阻力可能不同。本文研究了砂土中水平荷载作用下桩基础在冲刷作用下的响应，并考虑了剩余砂土的应力历史。计算了砂土由正常固结土（NC）变为超固结土（OC）时的相对密度和侧土压力系数。然后用相对密度来估计沙子的其他性质，例如，容重、摩擦角和地基反力模量。对砂土中桩的横向荷载-挠度曲线进行了修正，并将其输入到计算机软件LPILE Plus V5.0中，以考虑冲刷引起的应力历史的影响。并以现场试验为例，将修正后的p-y曲线计算结果与试验砂的初始p-y曲线计算结果进行了比较。结果表明，在剩余砂土性质变化引起的各种影响中，超固结比（OCR）的变化对土体侧阻力的影响最为显著。砂土从NC状态向OC状态的转变增加了桩基的侧阻力。忽略应力历史将导致冲刷作用下横向受荷桩的保守设计。
Scour is the removal of soils around pile foundations of bridges or offshore platforms, resulting in reduced capacity of the foundations in either lateral or vertical direction. A common way to analyze the scour-affected pile foundations is to remove the scoured soil layers while keeping the properties of the remaining soil unchanged. However, this approach ignores the fact that the remaining soil experiences different stress histories before and after scour, which can be expected to change the properties of the remaining soil. As a result, the resistance of the remaining soil provided to the pile foundation may be different. The present study focused on the response of laterally loaded pile foundations in sand under scour considering the stress history of the remaining sand. Relative density and coefficient of lateral earth pressure of the sand were evaluated when it changed from a normally consolidated (NC) soil to an over-consolidated (OC) soil due to scour. The relative density was then used to estimate other properties of sand, e.g., unit weight, friction angle, and modulus of subgrade reaction of the sand based on their correlation. The lateral load–deflection (p–y) curve for a pile in sand was modified and input into the computer software, LPILE Plus V 5.0, to account for the effect of the stress history induced by scour. A field test was referenced as an example to compare the calculated results from the modified p–y curves with those from the initially developed p–y curves for the tested sand. The results showed that the change in the over-consolidation ratio (OCR) resulted in the most significant effect on the lateral soil resistance among all the effects due to the changes in the properties of the remaining sand. The sand changing from an NC to OC state increased the lateral soil resistance to the pile foundation. Ignoring the stress history would result in a conservative design of laterally loaded piles under scour.