船锚入土深度简化计算方法及适用性研究

Simplified Calculation Method and Applicability of Anchor Depth

[目的]随着海洋经济的发展,越来越多海上风电送出、海上油气平台的供电、岛屿联网供电项目涉及海底电缆的敷设。目前主要的敷设保护方式为直埋敷设,但不考虑经济性的埋深设计显然是不合理的。为了能有效地保护海底电缆,又能合理控制投资,需要在项目开发阶段就确定海缆的合理埋设深度。因此,在缺乏足够的设计输入资料的情况下,文章提出了一种简化的船锚入土深度计算方法,为项目前期确定敷设保护方案提供依据。[方法]将船锚入土过程分成三个阶段建立数学模型,并对船锚入土过程进行了一系列边界条件假设。在此基础上,基于能量法对各个阶段船锚运动过程进行力学模型分析和推导,提出了考虑海底基质剪切破坏的船锚入土深度简化计算方法。通过将该方法的计算值与不同情况下的实测值进行对比分析,探讨该计算方法的适用性及适用范围。[结果]通过该简化方法计算值与实测结果比较分析表明,该计算方法适用于抗剪强度大于20 kPa的粘土的情况下计算船锚入土深度,且该方法的计算误差在可接受范围内。[结论]从计算结果对比分析可以看出,该简化计算方法对工程实践应用具有指导意义,但该方法还有待在实践中积累不同实测数据进行验证和拟合修正,并结合经验法和概率法进行分析,为海底电缆敷设保护提供设计依据。

[Introduction]With the development of Marine economy,more and more projects of offshore wind power transmission,offshore oil and gas platform power supply and island network power supply involve laying submarine cables.At present,the main laying protection method is direct burial laying,but the buried depth design without considering the economy is obviously unreasonable.In order to effectively protect the submarine cable and reasonably control the investment,it is necessary to determine the reasonable burial depth of the submarine cable in the project development stage.Therefore,in the absence of sufficient design input data,this paper proposes a simplified calculation method for the depth of anchor penetration,which provides a basis for determining the laying protection scheme in the early stage of the project.[Method]In this paper,the anchor penetration process was divided into three stages to establish mathematical models,and a series of boundary conditions were assumed for the anchor penetration process.On this basis,based on the energy method,we analyzed and deduced the mechanical model of the anchor movement process at each stage,and proposed a simplified calculation method of the anchor penetration depth considering the shear damage of the seabed substrate.By conducting a comparative analysis of the calculated values of the method and measured values under different situations,we explored the applicability and scope of the calculation method.[Result]The comparison between the calculated value of this simplified method and the measured result shows that this calculation method is suitable for calculating the depth of anchor penetration in the case of clay with shear strength greater than20 kPa,and the calculation error of this method is within the acceptable range.[Conclusion]From the comparative analysis of the calculation results in this paper,it can be seen that the simplified calculation method has guiding significance for the application in engineering practice,but the method still needs to accumulate different measured data in practice for verification and fitting correction,and combine the empirical method and probabilistic method for further analyses,to provide design basis for submarine cable laying protection.