考虑土隆发育的砂土中拖曳锚安装预测

    Prediction of Drag Anchor Installation in Sand by Considering Accumulation of Soil Heave

    • 摘要: 不同形式的深水锚均可用于系泊漂浮的油气平台或风机,其中拖曳锚因结构简单、综合成本低、拉重比高而成为了常用形式之一。在砂土中安装拖曳锚时,入土深度通常较浅,被拖动锚体的前方逐渐形成土隆,土隆显著影响被拖曳锚的入土深度和抗拉承载力,因此拖曳锚的安装预测分析需考虑土隆发育情况。基于此,本文提出了一种土隆发育模型,首先确定土隆计算边界,然后将逐渐累积的土隆自重作为锚体上覆土压力,用于求解拖曳锚抗拉力随拖动贯入的发挥过程。结合理论分析框架和提出的土隆发育模型,对比公开发表的离心机试验,验证了土隆发育模型的适用性。进而进行小比尺模型试验,定量评估了土隆对拖曳锚运动轨迹和抗拉力的影响。

       

      Abstract: Among different types of deep-water anchors for mooring floating oil and gas platforms or fans, the drag anchor is commonly used because of its simple structure, low overall cost and high anchor efficiency. When the drag anchor is installed in sand, the penetration depth is usually shallow, and soil heave gradually accumulates in the front of the dragged anchor. The soil heave has a significant impact on the penetration depth and holding capacity of the drag anchor, so the prediction on drag anchor installation should consider the accumulation of soil heave. Based on the this, the accumulation model of soil heave is proposed, at first the calculation boundary of soil heave is determined, and then the weight of the accumulated soil heave, as the overburden soil pressure on the anchor, is used for the process of the anchor holding capacity developed with the drag and penetration. The proposed accumulation model of soil heave was incorporated into the theoretical analysis framework to reproduce the existing centrifuge tests, and reasonable agreements were achieved. Then small-scale model tests were carried out, and the influences of soil heave on the holding capacity and motion trajectory of the drag anchor during installation were quantitatively evaluated.

       

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