Dynamic Model Test Study On Reservoir Pressure Effect Of Arch Dam

China is one of the countries with the highest reserves of hydropower energy in the world.A number of high arch dams have been built in southwest China.The southwestern region is an earthquake-prone area,and once dams are damaged under earthquake,it will cause huge losses.It is of great significance to study the seismic response of dam by dynamic model test and to evaluate the seismic safety of dam.At present,limited by the working ability of the shaking table and dynamic model test material,the dynamic model test is difficult to develop,especially the dynamic model test of dam-reservoir interaction.In the dynamic model test of dam with large scale,in order to meet the requirements of similar scale,a model test material with high density and low elastic modulus is needed.The high density can provide enough inertia force for the dam,and the low elastic modulus makes the deformation of the dam easier to detect and ensures that the dam will be damaged at a certain acceleration.When the density of the model material is higher than that of the prototype material,it is necessary to select a liquid whose density is higher than that of reservoir to carry out the experiment.Under the actual conditions,the liquid which meets the requirements of the similar conditions is almost non-existent.In order to solve the problem of inconsistent solid-liquid density in the dynamic model of dam-reservoir interaction,the following contents are studied:Based on the similarity relation of dynamic model test,the simulation concrete material is selected as dam model test material,and the material properties of simulation concrete are studied.It has high similarity with ordinary concrete material,and is a suitable dynamic model test material.The dynamic model test of dam-reservoir interaction is carried out with natural reservoir,and the seismic response of the dam is measured.Although it can not meet the requirements of solid-liquid density scale,it can correctly reflect the distribution law of hydrodynamic pressure on dam surface and the location of damage.When studying the damage condition of the dam,the Westergaard formula is reduced based on the hydrodynamic pressure distribution at the crown cantilever of the fracture stage of the dam.In order to solve the problem of inconsistent solid-liquid density scale,a spring-additional mass simulation system is proposed in this paper.The spring provides precise and adjustable hydrostatic pressure for the dam.The spring and the additional mass work together to provide the dam with suitable hydrodynamic pressure.The simulation system can provide the dam with reservoir pressure values that meet the different density scales requirements,adjustable,and make the dam material selection more convenient.The simulation system is used to carry out several groups of structural dynamic model tests.Compared with the natural reservoir storage condition,it is considered that the simulation system can correctly reflect the vibration characteristics and damage of the dam.In order to verify the reduction factor of the Westergaard formula,a reduced additional mass model is established based on the massless foundation model,and the seismic response of the model is compared with that of the finite element-infinite element and the massless foundation model.The results show that the finite element-infinite element can truly reflect the seismic response of the dam,and the massless foundation model exaggerates the seismic response of the dam.When the massless foundation model proposed in this paper is used for seismic response analysis,the reduction factor of the Westergaard formula can be used to simplify the calculation and improve the calculation efficiency.