关键词: 有效应力, 吸力, 抗拉力, 黏土, 有限元, 平板锚

Abstract:

The plate anchor is a new anchor foundation of moored deep-sea offshore floating structures. When a plate anchor is buried in the clay and subjected to uplift force, the difference of excess pore pressures on anchor top and base results in suction force, which may be beneficial to improve the uplift resistance of anchor, especially when wind and wave loadings apply quickly. A finite element software, ADINA, is used to establish axisymmetric dynamic finite element model in effective stress form. The distributions of excess pore pressure and failure mechanisms of foundation under fast and slow loadings of circular plate anchor are studied. In terms of two typical normally consolidated clays, gault and kaolin, under fast loading condition, the solutions of ultimate bearing capacity factor agree well with results from plastic limit analysis. By means of parametric analysis, the effect of loading rate and anchor embedment on suction force and limit value of total tension resistance are discussed. Furthermore, the critical loading rates corresponding to fully drained and undrained conditions are proposed. Numerical results show that the total tension resistance under undrained condition may be three times of the value under drained condition.

Key words: effective stress, suction, tension resistance, clay, finite elements, plate anchor