| Suction bucket foundations are more and more widely used in ocean engineering, the numerical analysis and the theory research of the installation procedure is helpful to guide engineering practice.A two-dimensional axisymmetric model has been established on the finite element software ABAQUS with the help of the ALE (Arbitrary Lagrangian-Eulerian formulation) technique to simulate the penetration process of the suction bucket foundation in clay. The undrained shear strength of soil and elastic modulus are varied with depth of soil through the subroutine VUFIELD. A centrifuge test and theoretical calculation are used for FEM model validation. After the validation, the penetration resistance, the height of soil plug under different suctions and the bucket wall friction have been examined. Based on the numerical results, it is shown that the ALE technique is able to simulate the suction bucket penetration without mesh distortion problems. The installation method can play an important role on the penetration resistance, namely, the suction penetration reduces the resistance significantly than the purely jacked penetration. Through a further study, it is found that as the final suction increases, the soil plug height increases, while the penetration resistance reduces with increases of the final suction. The effect of internal friction on the bucket wall has been also investigated and a conclusion is drawn that internal friction has a significant contribution to the penetration resistance and the properties of soil-bucket wall friction give rise to bigger impact to the resistance when the purely jacketed penetration than the suction penetration.According to the soil micro yuan period of force equilibrium, fully considering the soil elastoplastic state and internal seepage effect, bucket wall friction stress theory formula was derived. And using the large finite element software ABAQUS to establish numerical model for verification. In view of the seepage velocity, bucket wall friction coefficient and the bucket length to diameter ratio perform parametric analysis. The results show that the seepage will significantly reduce the internal friction stress. The results of friction stress from different seepage theory are very different, reasonable selection of seepage theory based on seepage velocity is important. The increase of bucket wall friction coefficient can cause the increase of bucket wall normal stress which makes the friction stress increases further. Increasing the bucket length to diameter ratio can increase the bucket wall average friction stress. But the inner bucker wall total friction with the bucket length to diameter ratio presents inverted parabolic form of change. Too big or too small bucket length to diameter ratio will increase the error of the theoretical formula.Because of the complexity of the Marine engineering problems, as well as the high cost and uncertainty of experimental study, through this study it can be seen that the numerical simulation is still effective approaches to the study of ocean engineering and its the basic structures. Large deformation finite element simulation technology study of suction bucket has achieved some success, but it should be improved further. Such as using the more appropriate constitutive model to describe special soil. Improve the speed of the ALE numerical calculation. Numerical simulation study of soil suction bucket also should further consider the micro meso and mesoscopic. |
PDF Full Text Request