Abstract:
Emergency anchoring operations pose a serious threat to the safety of subsea pipelines. Existing empirical formulas and theoretical models often show limited adaptability under complex geological conditions, particularly in characterizing the nonlinear evolution of soil strength during high-velocity penetration. To address this problem,this study takes the Hall anchor,which is widely used on merchant ships,as the research object and investigates the penetration behavior of ship emergency anchoring under static conditions using the Coupled Eulerian-Lagrangian(CEL) method. The Mohr-Coulomb constitutive model and the Einav strain-rate softening relationship are introduced to describe the dynamic degradation of soil strength. The anchor-soil contact interface is treated using the penalty function method,and an Eulerian domain with 586 000 elements is determined through a mesh convergence test. Taking the muddy clay in the waters of an offshore wind farm as the engineering background,the maximum penetration depths of emergency anchoring for a 20 000 GT LPG carrier and a 50 000 DWT oil tanker are calculated to be 2.908 m and 3.033 m,respectively. Compared with the DNV energy method and Young's formula,the proposed method can better reflect soil heterogeneity and large-deformation characteristics. The simulation results are further compared with experimental data,showing maximum errors of 13.1% in penetration depth and 16.1% in bottom-impact velocity,both of which are within the acceptable range for engineering applications. The results indicate that the proposed method has high reliability and is consistent with engineering practice,providing theoretical and technical support for subsea pipeline design,route planning,and anchoring risk control.