Research On The Seismic Hydrodynamic Pressure Of Plane Steel Gate

Plane steel gates as the control throat of high dams and large reservoirs,can adjust the overcurrent flow in real time and suppress fluctuations of power system,play an important role in high dams and large reservoirs.Most of high dams and large reservoirs is located in the southwest region,where the frequency of earthquakes is high,strong and destructive.Strong earthquakes will cause damage to plane steel gates.Under the seismic load,plane steel gate is subjected to hydrodynamic pressure generated by the water acting on the water facing surface,and this force changes with time,which constantly affects dynamic stability of plane steel gate.At present,the calculation of seismic hydrodynamic pressure of plane steel gate is in accordance with the"Code for Design of Steel Gates of Water Conservancy and Hydropower Engineering",and the dynamic method and quasi-static method are used to numerically meet the requirements of the gate design,however,Making the gate design more safe;In addition,the numerical model of the water-plane steel gate under earthquake action is a two-way fluid-structure coupling transient analysis,which is relatively complicated,but most models consider hydrodynamic pressure as additional mass force,or use one-way fluid-structure coupling model to simulation,as well as quasi-static analysis and response spectrum analysis,can not reflect the time-varying process of the plane steel gates during the seismic response,and ignoring the time effect of the entire earthquake.For this purpose,this article starts from the theoretical derivation and numerical simulation.First,combined the ideas derived from Westergaard and the basic knowledge of the related hydrodynamic pressure,to get the time-domain expression of hydrodynamic pressure.Then established a two-way coupled transient model of water-plane steel gate,obtains the distribution rule and maximum position of hydrodynamic pressure,and studies the influencing factors of hydrodynamic pressure from different aspects.The main research contents and results of this article are as follows:(1)Established the water-plane steel gate hydro-elastic coupling system model,considering the plane steel gate as elastic,and the displacement of the structure is expressed by linear combination of the modal vibration mode function _k?(y)and the generalized coordinates _kY(t).This article used Laplace changes to the fluid motion equations,boundary conditions and constraints in the built model,and the separation variable method to solve the fluid motion equations,to get the expression of hydrodynamic pressure in the time domain.(2)Based on finite element analysis theory,Transient structural is used as the structural domain solver,CFX is used as the fluid domain solver,and the system coupling with data exchange function is used as the data transmission channel between the structural domain and the fluid domain to establish the two-way coupling model of water-structure in the earthquake;Taking the classic gravity dam as an example,the transient response of the water-gravity dam model under the action of earthquake was solved by two-way fluid-solid coupling,obtained the pressure results of hydrostatic pressure and hydrodynamic pressure were compared with the results calculated by the standard formula and by the test,and the correctness of the two-way fluid-solid coupling numerical model established in this paper was verified.(3)For the water-plane steel gate two-way coupling model,the dynamic time-history method is used to obtain seismic hydrodynamic pressure distribution of the plane steel gate facing the water surface.The seismic hydrodynamic pressure distribution curve is composed of two paraboloids,and the paraboloid first increased,then decreased.In addition,the time-history change curve of the hydrodynamic pressure is consistent with the change trend of the seismic acceleration time history curve.(4)Combined with the two-way fluid-solid coupling transient model of the water-plane steel gate system,the water level height,to explore factors how to impact the distribution of seismic hydrodynamic pressure.By changing the water level height,it is found that the distribution trend of the hydrodynamic pressure curve for the five heights is basically same.As the water level height increases,the hydrodynamic pressure of corresponding control point is also increasing;By changing the stiffness of plane steel gates,it was found that the distribution curves of hydrodynamic pressure corresponding to the five kinds of stiffness basically coincide.with the increase of the stiffness,the hydrodynamic pressure corresponding to the five stiffness increases;The hydrodynamic pressure values of Tianjin wave,EI?CENTRO wave,Qianan wave are relatively close,and the overall distribution trend is basically the same,while the hydrodynamic water pressure of Lanzhou wave is numerically larger than these three waves,and the difference is up to 36%;The hydrodynamic pressure distribution curves corresponding to the EI waves with different peak accelerations basically overlap,and the difference in distribution values is small.