Onset of scour below pipelines and self-burial
Onset of scour below pipelines and self-burial
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DOI：
10.1016/s0378-3839(00)00066-1
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发表时间：
2001-04
影响因子：
4.4
通讯作者：
B. Sumer;Christoffer Truelsen;T. Sichmann;J. Fredsøe
中科院分区：
文献类型：
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作者：
B. Sumer;Christoffer Truelsen;T. Sichmann;J. Fredsøe
本文总结了水流/波浪中管道下方冲刷和自埋的试验研究结果。在浅埋管道表面的两个点上测量压力，一个在管道的上游侧，另一个在管道的下游侧，两者都在砂床中。后者能够计算压力梯度（驱动管道下方的渗流）。结果表明，过量渗流和管涌是引起管道冲刷的主要因素。冲刷的开始总是发生在局部（但不是沿着管道长度的二维过程）。在水流和波浪的情况下，确定了冲刷发生的临界条件。一旦冲刷发生，它将沿着管道的长度传播，冲刷坑被支撑管道的土壤（跨肩）中断。随着跨肩越来越短，管道施加在土壤上的重量越来越大。在这个过程中，达到临界点，超过土壤的承载力（一般剪切破坏）。此时，管道开始在跨肩处下沉（自埋）。结果表明，自埋深度主要受Keulegan-Carpenter数的影响。另一方面，自埋过程的时间尺度由Keulegan-Carpenter数和Shields参数决定。给出了自埋深度和自埋过程的时间尺度图。
This paper summarizes the results of an experimental study on the onset of scour below and self-burial of pipelines in currents/waves. Pressure was measured on the surface of a slightly buried pipe at two points, one at the upstream side and the other at the downstream side of the pipe, both in the sand bed. The latter enabled the pressure gradient (which drives a seepage flow underneath the pipe) to be calculated. The results indicated that the excessive seepage flow and the resulting piping are the major factor to cause the onset of scour below the pipeline. The onset of scour occurred always locally (but not along the length of the pipeline as a two-dimensional process). The critical condition corresponding to the onset of scour was determined both in the case of currents and in the case of waves. Once the scour breaks out, it will propagate along the length of the pipeline, scour holes being interrupted with stretches of soil (span shoulders) supporting the pipeline. As the span shoulder gets shorter and shorter, more and more weight of the pipeline is exerted on the soil. In this process, a critical point is reached where the bearing capacity of the soil is exceeded (general shear failure). At this point, the pipe begins to sink at the span shoulder (self-burial). It was found that the self-burial depth is governed mainly by the Keulegan–Carpenter number. The time scale of the self-burial process, on the other hand, is governed by the Keulegan–Carpenter number and the Shields parameter. Diagrams are given for the self-burial depth and the time scale of the self-burial process.