| With the continuous expansion of the city scale,the subway,as a convenient,efficient,green and environmental-friendly mode of public transportation,has developed rapidly in recent years,bringing convenience to people’s lives.However,with the encryption of the subway line network and the increase of subway speed,the vibration and noise caused by the subway train load have become an urgent problem in urban life.Chengdu city,as a new first-tier city,has a rapid and promising development of underground rail transportation,but there are few studies on the vibration transmission characteristics of subway under the characteristics of geological environment in this region.Therefore,for the transmission law of subway vibration load in soil in Chengdu area,there is an urgent need to carry out relevant research work to provide reference for vibration and noise reduction in the design and construction process of Chengdu area subway.Based on the Chengdu rail transit construction project,this paper takes the environmental vibration of Chengdu metro line 7 during the traveling process as the research object.Combining the test data,and through numerical calculations,the dynamic response characteristics of the soil under different driving environments are analyzed to determine the vibration attenuation law in accordance with the geological conditions in Chengdu.The main research contents and results are as follows:(1)The geotechnical test data of a large number of field samples of clay and sandy pebble soils in Chengdu area were analyzed for the statistical characteristics of their main physical and mechanical test parameters,and the distribution conditions and distribution laws of each parameter were derived.(2)For Chengdu clay and sandy pebble soil,the dynamic characteristics of the two soils under dynamic loading were investigated by dynamic triaxial tests,and the development of cumulative strain and dynamic parameters such as dynamic elastic modulus and damping ratio with dynamic strain were obtained for the two soils.(3)Using the finite element software,the equivalent linear model of the soil is analyzed and a model of the vibration transmission characteristics of the subway is established based on it.The propagation law of vibration acceleration in the soil medium under different driving environments is studied,and the environmental vibration spectrum analysis is thus carried out.Combined with the domestic environmental vibration evaluation standards,the impact range of vibration transmission of Chengdu subway is proposed. |
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