Study On Deformation Characteristics Of Underground Barrel Garage Under Earthquake

As our country’s urbanisation process continues to advance,traffic congestion and parking difficulties are becoming increasingly prominent.With limited land resources,it is imperative to maximise parking space and silo-shaped underground garages have been promoted as they can make full use of underground space and improve land utilisation.However,most cities in China are located in seismic zones,and the force and deformation characteristics of silo-shaped garages are more complex,which poses a great challenge to the operational safety of garages.Based on the basic principles of dynamics,shaking table model tests are carried out and combined with numerical simulations to analyse the dynamic force and deformation laws of silo-shaped garages under the action of earthquakes.The main conclusions of this paper are as follows:(1)Shaking table model tests of an underground silo-shaped garage based on similar theory show that the radial stress is minimum at the top of the silo and increases continuously along the burial depth direction,and the change in radial stress at the bottom of the silo wall increases from 0 ° to 90 ° decreasing.The soil is more sensitive to vibration frequencies in the range of 3 Hz and 3.5 Hz,when the vibration load propagates most efficiently in the soil,and the vibration amplitude has little effect on the variation of radial stresses in the silo wall.(2)The response characteristics of three different types,directions and amplitudes of seismic waves to the silo-shaped underground garage were investigated by establishing a three-dimensional model.The results show that the stress response of the structure increases along the burial depth direction,while the displacement and acceleration responses decrease continuously.The stress distribution pattern does not change with seismic waves,and the connection point between the side wall and the bottom plate of the silo-shaped garage is the most severely damaged part,which should be considered in the seismic design.(3)By optimising the parameters,the effect of different factors on the seismic performance of the silo-shaped garage is explored.The results show that when the stiffness increases above 1.5 EI,the stress increase decreases and the structural stiffness improves the seismic performance to a lesser extent.As the modulus of elasticity of the buried soil increases,the stress response increases and the displacement and acceleration response decreases.The stress response is more obvious in the adjacent parts of the silo,the stress response is the smallest in the three silo condition,the residual displacement of the single silo is the smallest,and the peak acceleration is not more related to the number of group silos.(4)The seismic response of the silo-shaped garage in the presence of liquefied soils is investigated by means of the liquefaction principal structure model in Midas/GTS,and the results show that the structure as a whole will be tilted upwards and the bottom plate will be mainly deformed in bending.A large horizontal residual displacement is generated at the end of the earthquake.The presence of liquefied soils inhibits the transfer of acceleration across the structure,with more pronounced changes at low amplitudes.