Study Of The Interaction Of Wave-seabed-pile

With the gradually pinch of land oil and mineral resources,people start to search for renewable resources and transform mining area from land to sea field.In recent decades,Offshore wind farm has become one of the hot spots in the development of marine renewable resources in China.When ocean waves propagate over a porous seabed,the dynamic pressure on seabed fluctuates with passing waves in complicated marine environment.Such fluctuations will further induce an excessive pore pressure,and then part of seabed may become instability or even liquefied.Once seabed is liquefied,the carrying capacity of seabed will sharply decrease which is very dangerous to ocean structure.Furthermore,when wave collides with a single pile or a couple piles,the wave will flow around the pile and the interaction of wave-pile will become intricate.Especially,the wave force around piles will significantly change while wave flow through a couple piles.The study of interaction of wave-seabed-pile can provide guidelines for engineering practice and avoid the occurrence of engineering accident.According to numerical model,this paper mainly studied the following contents:1.A three-dimensional wave-seabed numerical model is established.Linear wave,cnoidal wave,solitary wave and random wave are simulated and the wave induced dynamic response of seabed is studied.A parametric study including wave height,water depth,degree of saturation,permeability of seabed is carried out to analyze the change of pore pressure,effective stresses and liquefaction zone.At last,the different implications of pore pressure,vertical effective stresses,horizontal stresses,shear stresses,horizontal displacement induced by cnoidal wave,solitary wave and random wave is discussed.2.A three-dimensional wave-seabed-pile numerical model is established.In this model,k-? turbulent model is used to wave flowing around pile.The main work is studying the change of horizontal displacement of pile and pore pressure in front of pile with different parameters including Young's module of pile,the length of pile,Young's module of soil,density of soil,degree of saturation and permeability and the liquefaction of the soil around the pile foundation is analyzed.The results of study indicate that the horizontal displacement of pile is fast changing along the depth in sea water and changes slowly in seabed,the maximum bending moment of pile is occurred near the surface of seabed and the pore pressure in front of pile is changing rapidly at the top of seabed and is almost constant at other places.In addition,the liquefaction area will be more and more large while the permeability is smaller or the degree of saturation is bigger.3.A three-dimensional wave-seabed-cluster of piles numerical model is established.When three piles are placed in the direction of wave propagation and perpendicular to the direction of wave propagation,the horizontal displacement of pile,bending moment of pile and pore pressure of different piles are discussed.Wherein,the force of middle pile is greater than the side piles while three piles are placed in the direction of wave propagation,the force of pile is bigger while the difference of wave pressure in front of pile and wave pressure behind pile is lager and the pore pressure in front of pile depends on the value of wave pressure in the surface of seabed.