Simulation Of Vibration Effect Of Automatic Operating Trains And Parametric Analysis Of Soils

Speed limit is one of the most valid measures which can restrain the ambient vibration effect induced by the operation of subway trains.Using different Automatic Train Operation(ATO)system control strategy,the velocity and negative accelerate of the subway train when entering and leaving the station varies,which induces various ambient vibration re-sponses.Taking the underground structure of Xinghai Square in Suzhou as an example,the present paper is to build a finite element model and make use of Automatic Train Operation(ATO)system control strategy and the modified dynamic load empirical formula to figure out the train load when it pulls in and out of the station.Using field tests to verify the ra-tionality of the model,the paper carrys out a thorough study of the ambient vibration caused by the pulling in and out of trains under the control of ATO system and parametric analysis of soils.Conclusions are drawn as follows:(1)The pulling in of metro trains could induce vibration,namely Z vibration levels,in adjacent underground space.The greater the distance to the tunnel's center line is,the lower the Z vibration level is.The quick-reached strategy could bring about the maximum Z vibration,followed by the hybrid-optimized strategy,economy-comfort strategy and local-ly-sensitive strategy which leads to the minimum Z vibration.(2)Z vibration levels in adjacent underground space caused by the pulling out of metro trains shows the regularity similar to that of the pulling in of trains.But compared with the conditions of pulling in,Z vibration levels in various speed strategies have smaller differences.And when trains are pulling out,Z vibrations levels are lower than that of the pulling in of trains.(3)Z vibration levels in adjacent underground space caused by the pulling in of metro trains tend to decrease exponentially as the backfill damping ratio gets larger and reduce linearly as the soil dynamic shear modulus gets bigger.But the soil dynamic shear modulus has slight impact on Z vibration levels.(4)Elastic waves in ground caused by the running of trains weaken in clay or silty sand more dramatically than they do in silt or silty clay.