Simplified Calculation Method and Applicability of Anchor Depth

Abstract

[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 than 20 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.

Keywords

• submarine cable
• laying protection
• anchoring
• energy method
• shear strength