Field test on the inclined installation performance of dynamically installed anchors

Abstract

Dynamically Installed Anchor (DIA) utilizes high impact velocity via free fall to penetrate the seabed, offering efficient and low-cost mooring solutions. The embedment depth of DIAs depends significantly on installation quality, yet the inclined installation remains underexplored. This study conducted 19 field tests in clay, revealing embedment depths of 1.26–4.30 times the anchor length and inclination angles from 1.47° to 31.30°. Embedment depth loss remains minimal when the final inclination angle is within 14.69°, which occurs at an impact angle below 8.31° and an angular velocity under 4.99°/s. However, when the final inclination angle reaches 16.86°, embedment depth loss exceeds 0.5 times the anchor length. The inclination process consists of three stages: (1) a linear increase in inclination angle in the air with zero rotational moment; (2) a rapid followed by a gradual increase during initial penetration as soil resistance shifts the rotational moment from positive to negative; (3) stabilization at greater depths due to the surrounding soil resistance. A new effective diameter calculation method incorporating anchor inclination, applied to a logarithmic prediction formula, improves the accuracy. Comparative analysis shows that the resistance-based method is accurate with detailed soil data, while the energy-based method is efficient for preliminary assessments with limited soil information. This study provides practical insights into improving DIA installation reliability.