Model Test And Numerical Analysis Of Pull-out Capacity Of End-bearing Torpedo Anchor

When designing the mooring system of a deep-sea floating platform,it is necessary to determine the pull-out capacity of the anchoring structure installed in the seabed.The torpedo anchor is a new type of deep-water seabed anchoring structure with low installation cost and large pull-out capacity,which can be installed by free fall.Traditional torpedo anchors are similar to piles with a symmetrical tail.Its bearing capacity is mainly provided by the side resistance of the anchor body,and its pull-out capacity is closely related to the embedment depth.The end-bearing torpedo anchor is a new type of torpedo anchor.After installation,the end-bearing plate is opened by a special mechanism to form end resistance.The paper uses small scale model tests and numerical calculation methods to comprehensively analyze the bearing characteristics and influencing factors of end-bearing torpedo anchors,and compares them with traditional torpedo anchors.The main work is as follows(1)A small scale model test study on the bearing characteristics of end-bearing torpedo anchors.The model test was carried out in dry sand,and mainly analyzed the influence of factors such as the area of the bearing plate,the embedment depth,the relative density of the dry sand,and the drawing angle on the pull-out capacity.The test results show that under the vertical load,when the embedment depth is less than a certain value,the load-displacement curve of the universal torpedo anchor deforms smoothly and there is no peak point.The load-displacement curve of the end-bearing torpedo anchor has a peak point.Under the same test conditions,the pull-out capacity of end-bearing torpedo anchors is significantly higher than that of universal torpedoes.The increase in embedment depth and relative density can increase the pull-out capacity.Under horizontal load,the end-bearing torpedo anchor and universal torpedo anchor have similar bearing characteristics;under inclined loads,when the bearing plate area of the end-bearing torpedo anchor is larger than a certain value,its bearing characteristics are obviously better than those of the universal type.(2)Numerical calculation of bearing characteristics of end-bearing torpedo anchors and universal torpedo anchors.Using ABAQUS software,numerical calculations were carried out for two types of anchor types buried in the clay seabed(uniform soil and normal consolidated soil)at different depths.The influence of factors such as the position of the bearing plate,the embedment depth,the angle of drawing,the area of the bearing plate,and the nature of the soil on the pull-out capacity are mainly discussed.The calculation results show that in uniform soil,the position of the bearing plate and the area of the bearing plate have little influence when drawing horizontally.When drawing vertically,the position of the load-bearing board has less influence,and the area of the load-bearing board has a greater influence.In normal consolidated soil,when the bearing plate is at the bottom,the vertical pull-out capacity can be significantly improved.The maximum pull-out capacity of end-bearing torpedo anchors appears at different drawing angles as the area of the bearing plate increases.Increasing embedment depth can significantly increase the pull-out capacity of torpedo anchors.In normal consolidated soil,when the embedment depth of the torpedo anchor is 2 times the anchor length,under horizontal load,the rotation center of the end-supported and traditional torpedo anchors is about 0.7anchor length away from the anchor end.The failure mode of the end-bearing torpedo anchor is the local shear failure at the anchor end and the bearing plate,and the fracture surface extends a certain length of the anchor rod.Established the end-bearing torpedo anchor V-H damage envelope.