Seabed trenches, as a geological hazard, adversely influence the safety of adjacent anchors. Seabed trenches predominantly appear in the Gulf of Guinea, where the seabed soils exhibit some features, e.g., high plasticity, high water content and low shear strength. However, the marine engineering geology where seabed trenches appear is not well understood, as well as the trenching process related to soil erosion. In this paper, the information about seabed trenches was summarized, and marine engineering geology where seabed trenches appear was analyzed in detail. It was found that the marine clay with high plasticity index, high organic content, higher sensitivity, low effective unit weight and shear strength is easier to form seabed trenches. Then, penetration tests of a chain-bar penetrometer were conducted to investigate the soil deformation and erosion near the surface. Experimental observations reveal that the normalized soil resistances from both penetrometers exhibited similar trends, despite different soil deformation mechanisms. In the cyclic tests, the soil resistance was degraded significantly in the first 20 cycles, and water flow induced by chain motion eroded the soil particles near the chain links. This study provides insights into the marine engineering geology and development process of seabed trenches.

中文翻译：

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根据海洋沉积物特性和链杆贯入试验评估海底沟的形成


海底沟槽作为一种地质灾害，会对相邻锚的安全产生不利影响。海底沟渠主要出现在几内亚湾，那里的海底土壤表现出一些特征，例如高塑性、高含水量和低剪切强度。然而，出现海底沟槽的海洋工程地质以及与水土流失相关的挖沟过程尚不清楚。本文总结了海底海沟的信息，并详细分析了海底海沟出现的海洋工程地质。研究发现，塑性指数高、有机物含量高、敏感性高、有效单位重量和剪切强度低的海相粘土更容易形成海底沟。然后，对链杆触探仪进行触探试验，以调查地表附近的土壤变形和侵蚀。实验观察表明，尽管土壤变形机制不同，但两种渗透计的归一化土壤阻力表现出相似的趋势。在循环试验中，土壤阻力在前 20 次循环中显着下降，链运动诱导的水流侵蚀了链节附近的土壤颗粒。本研究为海底海沟的海洋工程地质和发育过程提供了见解。