Seismic Dynamic Response Analysis Of High-rise Intake Tower Under Different Boundary Conditions

The intake tower can be used as a diversion structure or a drainage structure.The connection form between the intake tower and the surrounding ancillary buildings is complex,and the foundation conditions are diverse.There are dozens of meters of hoist room at the top of the tower body,and it is surrounded by internal and external water bodies.Secondly,there is mutual contact between the bottom of the intake tower and the bedrock,and between the backfill concrete and rock mass.Under the action of earthquake,due to the complex boundary conditions of the intake tower,the different boundary conditions have a significant impact on the dynamic response of the intake tower structure,and the mechanism is complex.It is necessary to further systematically and deeply analyze the dynamic response of the intake tower structure.In order to study the dynamic response law of different boundary conditions on intake tower under strong earthquake,this thesis firstly analyzes the dynamic response law of intake tower-water body under fluid-solid coupling boundary conditions based on viscous fluid theory.Secondly,on the basis of considering the material nonlinearity of intake tower,the seismic dynamic response under the nonlinear contact boundary condition between tower and bedrock is discussed.The findings are as follows :(1)Under the action of earthquake,the tower and fluid structure are regarded as a system,and the viscous fluid theory and Arbitrary Lagrangian-Eulerian(ALE)method are used to describe the fluid.Through the calculation of Pearson correlation coefficient,the feasibility of the fluid-solid coupling numerical method and model in this thesis is verified by KOYNA gravity dam.On the basis of this theory,the dynamic response law of intake tower structure under fluid-solid coupling boundary conditions is explored.(2)The fluid-solid coupling boundary conditions of intake tower-water body are studied.In this thesis,the concept and basic theory of fluid-solid coupling boundary condition are discussed in detail.According to its principle and additional mass method,the displacement,acceleration and stress are compared and analyzed.It is concluded that the seismic response of intake tower structure can be reduced by considering fluid-solid coupling effect.The influence of various influencing factors on the dynamic response of the intake tower structure under the convection-solid coupling boundary condition is studied.The displacement at the top of the intake tower,the maximum principal stress at the bottom of the tower and the height of the liquid surface wave are used as the response indexes to analyze the influence of different site seismic waves,the compressibility of the water surface,the fluctuation of the liquid surface,the height of the water level and the bidirectional seismic waves on the convection-solid coupling effect.It is concluded that considering the FSI effect,under the action of the same seismic wave,the displacement and acceleration at the top of the intake tower gradually decrease with the gradual increase of the water level.(3)The nonlinear boundary conditions of contact between intake tower and bedrock are studied.On the basis of considering the material nonlinearity of intake tower,contact elements are set on the contact surface between intake tower and bedrock to study the influence of contact nonlinear boundary condition on dynamic response.The influence of intake tower structure,backfill concrete and bedrock on the tower under earthquake is analyzed.Through the analysis of the relative displacement time history curve at the top of the intake tower under the action of earthquake,the contact surface state around the tower body,the damage energy of the tower body and the evolution process of damage and cracking,it is concluded that the relative displacement amplitude under the condition of considering contact is 31.12 % higher than that without considering contact nonlinearity.From the evolution diagram of the tensile damage development process of the tower body,without considering the contact nonlinearity,the tower body of the intake tower runs through the damage area at the elevation of 2663.0 m,which is at the interface of different concrete materials.Considering the contact nonlinearity,the damage area of the tower body includes the interface of concrete materials at the elevation of 2663.0 m and the geometric mutation of the upper surface of the diversion tunnel.From the damage dissipation energy curve of the tower body,the damage dissipation energy considering contact nonlinearity increases by 34.06 % compared with that without considering contact nonlinearity.Based on the conclusions of displacement,damage cloud and energy curve,it can be concluded that the damage model of intake tower is unsafe under the condition of considering contact nonlinearity,but the intake tower model is closer to the actual situation.