| Because of the complexity of the marine environment and loading conditions,anchor plates may be installed on some slope of the seabed to achieve some exploration purpose.The uplift bearing capacity of anchor plates directly determines the stability of offshore structures.Therefore,the ultimate uplift capacity of anchor plates on marine slopes is worth studying.With the depth gradually into the deep ocean exploration field,is widely application of New-type Drag anchors.The new drag anchor has the advantages of convenient deep water installation,but the final submergence position is still difficult to be accurately determined.At present,the feasible way to evaluate the diving depth of towing anchor is to deduce the anchor’s diving position according to the position of anchor chain,anchor chain tension and anchor chain equation.The force condition of anchor chain directly affects the shape of anchor chain,so the stress characteristic analysis of anchor chain is particularly important.The engineering practice shows that the high sensitivity marine soft soil has obvious strain softening characteristics and it can result in the decrease of the bearing capacity of the drag anchor and the instability of offshore platform under large deformation conditions.Therefore,the research on the embedment mechanism and motion characteristics of deep water anchor in the seabed and the influence of strain softening on the ul timate bearing capacity of drag anchor are important contents in deep sea engineering,especially in marine geotechnical engineering.Based on the large deformation finite element analysis technology coupled with the Eulerian-Lagrangian method,the motion characteristics and embedding mechanism of the new drag anchor and the influence of strain softening on the ultima te bearing capacity of the drag anchor are explored through numerical simulation.The first part of the thesis explores the numerical analysis of the ultimate upli ft bearing capacity of strip anchor plate in sloping foundation.First,the uplift bearing capacity of anchor plate in horizontal foundation is calculated,and the calculated results are in good agreement with the existing literatures.Under the condition of uniform soil and normal consolidated soil,the effect of different slope angle,different bonding methods between anchor-soil(Vented and Attached)and different embedment angles(θ=0°andθ=90°)on ultimate uplift capacity of strip anchor plate is studied.By using the coupled Eulerian-Lagrangian method,the second part of the thesis investigated the effect of strain softening on the ultimate uplift capacity of the drag anchor in clay using the user subroutine VUSDFLD.It is found that the peak bearing capacity of the drag anchor is almost unaffected by the strain softening of clay,but the residual bearing capacity of the anchor is greatly influenced by strain softening.The third part of the paper established a three-dimensional anchor chain soil anchor interaction model,which simulates the embedded installation process of the drag anchor.The LINK element is used to simulate the cable structure,and the force and deformation law of the cable is explored by changing the different design angles of the drag anchor.The calculation results can clearly observe the reverse catenary chain shape of the cable under different design angles,and get the embedding rule and the force characte ristic of the drag anchor with the design angle.Secondly,through changing the different values of N_c andμ,revealed the effects of N_c andμvalues when deriving drag forces using theoretical solutions. |
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