Seismic Analysis Of High-rise Intake Towerand Study On Dynamic Response Of Tower Groups

With the continuous improvement of darm construction technology in China,the darn projects of more than 200m level have been built one after another,and the heigh of the corresponding intake structures has also inereased.As the water intake building commonly used in water conservancy projects,the water intake tower is mostly below the water surface and has a complicated force.Because the intake tower is a high-rise stricture,it is oftern damaged by earthquake.As the first building of power generation,irrigation flood discharge and venting systems,the failure of intake tower will not only lead to the normal operation of the whole water control project,but also seriously endanger the safety of the darm,and indirectly threaten the lives and property of people in the downstream of the reservoir.Therefore,it is of great significance to study the seismic behavior of high-rise intake towers.In this paper,three-dimensional finite element method is used to analyze the displacement and stress distribution of tall intake tower under static and dynamic(earthquake)conditions.Simultaneously,the dynamic response of intake tower group is studied.The main research results include:(1)Through the calculation and analysis of the individual tower,it is found that:The most dangerous conditiocn of tower under static load is construction completion condition;Compared with non-seismic conditions,the displacement and stress of the tower under seismic conditons are signifricantly increased,and the displacement of the tower under seismic conditions is mainly the vertical water flow displacement;The intake tower is mostly un der pressure,and the tension stress zone mainly occurs at the joints of transverse connecting beam,longitudinal connecting beam,backfill concrete top s:urface and bedrock,trash barrier pier,tower bottom plate,runner top plate,the connection between the downstream surface of tower and backfill conerete top surface etc.(2)Through the study of the self-vibration characteristics of the individual tower,it can be seen that the basic frequency of the intake tower is mainly the vibration of the vertical flow direction,and the high-order vibration mode is mainly the vibration of the trash barrier pier.(3)The natural vibration characteristics of intake towers are studied and it is found that:For a certain mode,the natural frequencies of towers with contacts between towers are larger than those with cracks between towers.However,in both cases,the fundamental frequencies of the towers are mainly in the direction of vertical water flow,and the high-order modes are mainly in the vibration of the trash barrier piers.In the case of contact between the towers,the integrality of the towers is strong,the synchronous vibration of the towers is basic;the integrality of the towers is weak in the case of cracks between the towers,and there is obvious relative deformation in the structure of the towers.It is necessary to further study the relative displacement of the towers in order to prevent the collision between the towers under earthquake.(4)After studying the displacement and stress distribution of intake towers under earthquake,it is found that:The displacement of the whole group of towers decreases when there is contact between towers,but the location of the maximum displacement does not change,and the displacement of the whole group of towers is mainly vertical flow direction displacement;The stress law of the tower group is similar to that of the displacement law.The overall stress of the tower group decreases when the contact between the towers is set,but the maximum value does not change when the joints between the towers occur.It basically occurs on the connecting beams.(5)Study on the collision phenomenon between tower groups under earthquake action and it is found that:Under the action of vertical flow direction earthquake,the transverse joints between towers of tower group open and close,that is,the towers are squeezed and collided with each other.The maximum relative displacement of towers close to each other is larger when there is a gap between towers;The maximum contact pressure between the towers is small,which is 1.36 MPa,when the tower is in contact with each other,which is less than the compressive strength of the concrete and does not cause damage to the concrete.