Study of Seepage Flow And Sand Plug Loosening In Installation of Suction Caissons In Sand
Study of Seepage Flow And Sand Plug Loosening In Installation of Suction Caissons In Sand
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发表时间：
2005
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影响因子：
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通讯作者：
M. N. Tran;M. Randolph;D. Airey
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作者：
M. N. Tran;M. Randolph;D. Airey
众所周知，渗流在辅助砂中沉箱负压安装中起着关键作用。通过沿着沉箱内壁和壁尖处的砂松动，水流显著降低了土壤阻力。同时，这也会造成堵塞物松动和沉箱内砂柱向上运动。尽管在现场试验和小规模实验研究中被广泛观察到，但在吸力安装过程中的渗流行为和砂塞松动程度还没有得到很好的理解。为了研究这一问题，在土工离心机中进行了一系列试验。在每个测试过程中的渗流推导和比较的结果从1g测试。用PLAXIS软件对理论渗流进行了计算，并与实验结果进行了比较。通过渗流反算检查了试验中堵塞松动的程度，并使用先前开发的空隙率渗透率关系对记录的砂胀进行了检查。结果发现，在安装过程中，最初致密的砂塞似乎处于中等状态。理论膨胀和记录的起伏之间的比较给出了良好的协议。CPT测试也在吸力安装的沉箱内进行，并清楚地显示了塞子松动的证据。试验是使用不同尺寸的沉箱进行的。还将讨论离心机中渗流的缩放。
It is well known that seepage flow plays a key role in assisting suction installation of caissons in sand. By loosening sand along the caisson’s inner wall and at the wall tip, the flow significantly reduces the soil resistance. At the same time, this can also create plug loosening and upward movement of the sand column inside the caisson. Despite being widely observed in both field tests and small-scale experimental studies, the behaviour of seepage flow and the extent of sand plug loosening during suction installation are not well understood. To investigate the problem, a series of tests were conducted in a geotechnical centrifuge. Seepage flow during each test was derived and compared with results from the 1g tests. Theoretical seepage was also calculated using PLAXIS, whose results were then compared with the experimental ones. The extent of plug loosening in the tests was examined through seepage back-calculations, and checked against the recorded sand heave using a previously developed void ratiopermeability relationship. It was found that the initially dense sand plug appeared to be in medium state during installation. Comparisons between theoretical expansion and recorded heave gave good agreement. CPT tests were also conducted inside the suction-installed caissons, and clearly showed evidence of plug loosening. The tests were carried out using caissons of different sizes. Scaling of seepage flow in the centrifuge will also be discussed.