Runout prediction and dynamic characteristic analysis of a potential submarine landslide in Liwan 3-1 gas field
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摘要: 荔湾3-1气田管道路由区峡谷段内存在数目众多、规模不一的海底滑坡且仍具有发生的可能性, 其一旦发生将给海底管道带来较大威胁。针对该区域潜在的海底滑坡, 引入欧拉-欧拉两相流模型预测斜坡失稳后的土体运动。海底滑坡土体与环境水分别采用Herschel-Bulkley流体和牛顿流体模拟, 湍流采用k-ε模型计算。通过与实验数据及BING模型对比, 两相流模型具有较高的准确性, 能够有效处理滑动土体与环境水的动力耦合问题, 可获得滑动土体端部滑水和拆离现象, 预测结果更接近实际。最后基于实际地震剖面对潜在海底滑坡进行预测分析。结果表明, 算例滑坡土体滑动过程中发生滑水, 两相流模型预测滑移距离为877m比BING模型预测值大27.1%, 但端部峰值速度相对较小, 最大峰值为8.32 m/s。BING模型计算简单快速适合前期评估, 两相流模型计算量较大适合精确评估。
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关键词:
- 海底滑坡 /
- 欧拉-欧拉两相流模型 /
- Herschel-Bulkley模型 /
- 滑水
Abstract: A large number of submarine landslides with different scales have been identified in the canyon area of the submarine pipeline route of Liwan 3-1 gas field. There is still much chance that submarine slope failures would happen, and the following mass movement would present great risk to the submarine pipeline. In view of this, a numerical prediction method based on Eulerian-Eulerian two-phase flow model is introduced to simulate the mass movement of potential submarine landslides. The sliding soil and ambient water are respectively simulated by Herschel-Bulkley rheology model and Newtonian fluid model. The turbulence is simulated using the k-ε model. Compared with both the experiment data and Bing result, the two-phase flow model shows a good accuracy, and its result is more close to the actual situation; the dynamic coupling between soil and ambient water can be effectively simulated and the phenomena of hydroplaning and head detachment can be obtained. Finally, the soil movement of a potential submarine landslide is simulated as an example, according to the seismic profile in the canyon area. The result shows that the hydroplaning occurs during the movement process. The runout distance calculated by the two-phase flow model is 877 m, which is 27.1% larger than the Bing result. However, the peak front velocity of soil is relative small, with a maximum value of 8.32 m/s. The Bing program with a simple and rapid process can be used for a preliminary evaluation, while the two-phase flow model is more appropriate for an accurate assessment. -
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