航道区碎石层对霍尔锚落锚条件下海底管道防护效果研究

航道中船舶抛锚作业使海底管道可能受意外撞击，造成管道局部损伤甚至失效，进而对油气生产安全和生态环境等造成重大危害。采用碎石层防护是航道区等海域海底管道最常用的防护手段。首先基于大比尺落锚模型试验，观测了霍尔锚下落贯入碎石的3个阶段及其贯入过程中管道的应力应变状态。通过建立光滑粒子流体动力学法（SPH）和有限元法（FEM）耦合的数值模型，针对实际不同吨位通航船舶常用的霍尔锚，研究了其贯入碎石层深度及埋设管道受力和凹陷变形规律。最后分析了不同锚质量、碎石层形状和厚度等因素下埋设管道的响应规律。结果表明：采用暗埋式碎石防护层有利于撞击能量吸收，能更好地防护海底管道受损；且采用3 m以上碎石防护层能有效保护海底管道抵抗各类实际常见霍尔锚的撞击损伤。

Study on the protection effect of the gravel layer in the channel area on submarine pipelines under hall anchor dropping conditions

The anchoring operations of vessels in navigational channels may result in accidental impacts on submarine pipelines, causing local damage or even failure, thereby posing significant hazards to oil and gas production safety and the ecological environment. The use of a gravel layer for protection is the most common method for safeguarding submarine pipelines in navigational channel areas and similar marine environments. Firstly, based on large-scale anchor model tests, three stages of anchor penetration into the gravel layer under hall anchor dropping conditions were observed, along with the stress and strain states of the pipeline during penetration. By establishing a numerical model coupling Smoothed Particle Hydrodynamics (SPH) and Finite Element Method (FEM), specifically for hall anchors commonly used by vessels of different tonnages, the depth of penetration into the gravel layer and the stress and deformation characteristics of the buried pipeline were studied. Finally, the response patterns of buried pipelines under different anchor masses, gravel layer shapes, and thicknesses were analyzed. The results indicate that the use of a submerged gravel protection layer facilitates energy absorption during impacts, providing better protection for submarine pipelines. Moreover, a gravel protection layer with a thickness of over 3 meters effectively shields submarine pipelines against damage from various common hall anchors.