Transparent Soil Tests For Effects Of Padeye Offset Ratio And Fluke Angle On Travel Trajectory Of Fixed Fluke Drag Embedded Anchor

The mooring foundation is set up in the seabed to resist the tension for the moor offshore floating structures.Due to the advantages such as light weight,easy installation,economy,reusable performance and so on,the fixed fluke drag embeded anchors(FFDEAs)are widely used.The centrifuge experiments and model experiments are the main method to study the travel trajectory of the FFDEAs in the soil.For the soil is opaque,in some experiments the soil is cut to observe the travel trajectory of the FFDEAs.In the other experiments the sensors are employed to measure their travel trajectory.However the desire results can not be achieved by above methods.Therefore,how to directly observe the travel trajectory of the FFDEAs in the soil is a key issue to study the laws of the movement of the FFDEAs.The thesis is financially supported by the National Natural Science Fund projects of "Post-peak mechanical properties study for saturated-unsaturated rock with confining pressure"(Nos.51274079),and "Mechanism study on fracturing low-permeability coal bed through liquid nitrogen injection"(Nos.51574139)and Hebei province Natural Science Fund project "Study on the geotechnical mechanism of deep water plate anchor"(Nos.E2015208089).Then the transparent dragging testing setup is made.The efforts of the padeye offset ratio and fluke angle on the travel trajectory of the FFDEAs are experimentally investigated.A new experiment method on research the motion properties of FFDEAs is provided.The main contents are:1)The transparent soil obtained from the fused sillica and aquabeads transparent soil were made.2)The experiment dragging setup comprised of glass flume,drag system,image acquisition and processing system and transparent soil wad made.3)Using the experiment setup,the penetration experiments of the FFDEAs were performed,and the effects of the padeye offset ratio and fluke angle on the travel trajectory were investigated.4)The Neubecker model was employed to predict the travel trajectory of the model anchor in this paper.The main conclusions in this paper are:1)The travel trajectory f the FFDEAs can be directly observed by the self-made transparent dragging experimental setup in this paper.A new experiment method to research the motion properties of the FFDEAs is provided in this paper.2)The padeye tangential offset and the padeye eccentricity are not independent.The padeye offset ratio instead of the padeye tangential offset and the eccentricity can better describe the effects of the padeye offset on the travel trajectory.3)The fluke angle is an important parameter to influence the travel trajectory of the FFDEAs in soil.With the fluke angle increasing,the ultimate penetration depth of the fixed fluke drag embedded anchor firstly creases and then decreases.The recommended fluke angle for very soft soil is 50°to 60°.4)With the increasing of the padeye offset ratio,the ultimate penetration depth of the fixed fluke drag embedded anchor firstly creases and then decreases.The recommended padeye offset ratio is 0.3.5)The Neubecker model can better predict the travel trajectory of the FFDEAs in the soil.