Shaking Table Test Of A Subway Station In Xi’an

With the rapid expansion of China’s urban scale,surface traffic congestion has become the norm.Metro stations have become an important way to relieve ground transportation resources due to their advantages of high carrying capacity and reduced ground space occupation.China’s metro construction is developing rapidly,and Xi’an is also in the stage of metro station construction in full swing.However,the research on the seismic performance of subway stations in China is relatively lagging behind.According to the data of previous earthquake disasters,once the main structure of subway station is damaged under the action of earthquake,the damage will be very heavy and the repair cost and difficulty are extremely high.Therefore,based on the "Research on Urban Underground Space Utilization under High Intensity Disaster Geological Environment of Greater Xi’an(2021SF2-02)",a key research and development project of Shaanxi Province,in this paper,the seismic response regularity of Xi’an Hang Tian Cheng subway station is investigated by shaking table test and finite element simulation,which can provide a reference value for the seismic research of the subway station.The main research contents and results are as follows:(1)Using the Xi’an Hang Tian Cheng subway station as the prototype construction,similarity ratios were designed for each parameter in this test based on the similarity theory,and a model structure with a geometric similarity ratio of 1/30 was fabricated using particulate concrete.At the same time,the mix ratio design and mechanical properties of the particulate concrete were carried out to verify that it conforms to the requirement of the material similarity ratio of the prototype structure,and to restore the damage pattern of the prototype structure under the earthquake to the maximum extent.(2)According to the actual site conditions of Xi ’an Hang Tian Cheng Metro Station,this paper selected Elcentro wave,Taft wave,Chichi wave and fitted Xi ’an artificial wave to carry out shaking table tests of model structure under various working conditions,so as to study the response law of model structure of metro station under earthquake.The test results show that the layered shear soil box selected in this paper and the treatment of the model box boundary can eliminate the reflection of the model box boundary on seismic waves.In addition,With the increase of the input peak acceleration,the peak acceleration of each test point in the model foundation and the model construction shows an increasing trend.The peak acceleration and amplification coefficient of each measurement point in the model foundation will increase with the decrease of soil depth,while the peak acceleration and amplification coefficient of the model structure will increase with the increase of structure height.At the same time,the strain amplitude of the column and slab elements in the main observation plane of the model structure increases with increasing the input peak acceleration.The strain response at the top of the upper column and the bottom of the lower column is more significant,and the strain amplitude at the top slab of the model structure is larger than that at the middle and bottom slab.In addition,with the increase of the input peak acceleration,the earth pressure at the side walls of the structure also increases,while the earth pressure amplitude at the height of the middle slab is the largest compared to that of the middle slab,the horizontal displacement amplitude of the model foundation also increases.The horizontal displacement amplitude of the model foundation increases with the decrease of the depth of soil layer.(3)Using ABAQUS software,a finite element numerical model of the subway station was established and computational analysis was carried out.By comparing the simulation results with the test results,it can be found that the seismic response law of the model structure of the subway station under the finite element simulation and shaking table test is basically consistent,which verifies the dependability of the finite element numerical model built in this study.Based on this finite element numerical model,the stress analysis of the model structure of the subway station was carried out.The results show that under the seismic action,the large stresses develop at the joints between the slab members and the side walls of the subway station,as well as the bottom of the lower column and the top of the upper column of the central column,and these locations are the seismic weak parts of the subway station structure,which should be emphasized in the seismic design.