Simulation and evaluation of improvement effects by vertical drains/vacuum consolidation on peat ground under embankment loading based on a macro-element method with water absorption and discharge functions
Simulation and evaluation of improvement effects by vertical drains/vacuum consolidation on peat ground under embankment loading based on a macro-element method with water absorption and discharge functions
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DOI：
10.1016/j.sandf.2015.09.007
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发表时间：
2015-10
影响因子：
3.7
通讯作者：
H. Nguyen;M. Tashiro;Motohiro Inagaki;S. Yamada;T. Noda
中科院分区：
文献类型：
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作者：
H. Nguyen;M. Tashiro;Motohiro Inagaki;S. Yamada;T. Noda
作者之前扩展了 Sekiguchi 提出的宏观单元方法，将吸水和排水函数纳入其中，并将其纳入能够考虑惯性力的土水耦合有限变形分析代码中。本研究的主要目的是通过将模拟结果与通过垂直排水和真空固结改进的软泥炭地基路堤荷载的实际测量结果进行比较，验证所提出的方法模拟实际地面行为的能力。结果发现，该方法不仅能够全面、密切地模拟沉降量，而且能够模拟各种地面行为，包括周围地面的变形和孔隙水压力分布。此外，还进行了额外的模拟，以阐明在实际路堤工地上存在的连续中间砂层的影响，并跨越整个改善区域。本研究的下一个目标是研究地面改善的影响，在软土地基上使用垂直排水管和真空固结以及路堤荷载，特别关注排水管间距的影响。在本例中，对具有交替泥炭层和粘土层的超软地面进行了建模，以代表将应用真空固结的典型地面。基于一系列的模拟发现，虽然在需要限制周围地面变形的情况下，真空固结与垂直排水管的结合使用是有效的，但只要排水管的部署频率足够，单独使用垂直排水管也可以实现相同的残余沉降减少效果。
The authors previously extended the macro-element method proposed by Sekiguchi to include water absorption and discharge functions and incorporated this into a soil–water coupled finite deformation analysis code capable of accounting for inertial forces. The primary objective of this study is to validate the ability of the proposed method to simulate actual ground behavior by comparing the simulation results with the actual measurements of the embankment loading of a soft peat ground improved with vertical drains and vacuum consolidation. It was found that the proposed method is capable of comprehensively and closely simulating not only the magnitude of settlement, but also various ground behaviors, including the deformation of the surrounding ground and pore water pressure distributions. Furthermore, additional simulations were performed to elucidate the effect of a continuous middle sand layer found to exist and to span the entire improved area at an actual embankment site.The next objective of this study is to investigate the impact of ground improvement, using vertical drains and vacuum consolidation with embankment loading on a soft ground, placing a particular focus on the effect of drain spacing. In this case, an ultra-soft ground with alternating peat and clay layers was modeled to represent a typical ground to which vacuum consolidation would be applied. Based on a series of simulations, it was found that, although the use of vacuum consolidation in combination with vertical drains is effective in cases where it is necessary to limit the deformation of the surrounding ground, the same reduction in residual settlement can be achieved using vertical drains alone, provided that the drains are deployed at a sufficient frequency.