Study on penetration resistance and infiltration field characteristics of bucket foundation
[Objective]During the installation of bucket foundation,the negative pressure applied not only provides downward driving force for the bucket foundation,but also generates an infiltration field from outside to inside during the penetration process.External seawater infiltrates into the bucket foundation after bypassing the end.In order to investigate and evaluate the changes in the effective stresses in the surrounding soil under the action of this seepage field,as well as the effects on the friction of the inner and outer walls of the barrel base and the changes in the end bearing capacity,a study was carried out to investigate the sedimentation penetration resistance of the homogeneous seabed and the layered seabed.[Methods]In this paper,finite ele-ment software COMSOL Multiphysics was used to establish two-dimensional axisymmetric models of saturated sandy soil,clay,and layered soil bucket foundations during penetration installation using numerical simulation,to explore and evaluate the changes in penetration resistance under the influence of the infiltration field.[Results]The result indicate that the infiltration field has a noticeable reduction effect on the penetration of bucket foundations in sandy seabeds.The total penetration resistance decreases by over 30%when negative pressure is applied.However,the impact on clay seabeds is relatively minor.The distribution of the infiltration field in homogeneous seabeds exhibits similar characteristics.For the case of a sandy layer overlying a clay seabed,the presence of the clay layer suppresses the infiltration,Resulting in a 20%increase in penetration resistance compared to hom-ogeneous sandy soil.In the scenario of a clay layer overlying a sandy seabed,the weakening of negative pressure due to the clay layer leads to a 36%increase in penetration resistance compared to a homogeneous clay seabed.[Conclusion]The result show that the applied negative pressure provides vertical force to the barrel foundation on one hand,and reduces the resistance to sink-ing through on the other hand.However,the situation is more complex in layered seabed compared to single sand or clay seabed,as various seepage elements undergo abrupt changes at the soil condition interfaces,which may easily lead to soil damage inside the bucket foundation.This research aims to provide more convenient and effective theoretical guidance for on-site installation and construction.
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