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

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.