Study On Influences Of Vibration Induced By Metro Depot Trains On The Buildings Nearby And Isolation Measures

With the process of urbanization in China,the population is crowded into cities,and the urban buildings are more and more intensive,it is inevitable that buildings will be built near the existing subway lines;at the same time,the influence of subway vibration on people’s daily life and work is becoming more and more prominent as the people s demands for the quality of life gradually increase.However,the current research on the impact of vibration induced by metro depot trains on adjacent buildings and vibration isolation measures is not perfect.Relying on the integrated development project of a metro depot in Beijing,the new building is 3 floors underground and 27 floors on the ground,the subway is a U-shape structure,and the distance between the new building and the existing subway is about 30m.Through the site test of the new building,the distribution of the vibration in the building is analyzed;and then the propagation law of the subway vibration in the soil and the building are simulated by establishing vehicle-track model and FEM of Track-Sub rail foundation-Soil-Building,the isolation effect of vibration isolation measures such as empty ditch and filling ditch is put forward and demonstrated.According to this project,we get the following research results:(1)Through on-site measurement of the building,the distribution of vibration in each floor of buildings is analyzed,and the correctness of the numerical simulation method is verified by comparing the numerical simulation results with the measured results.The evaluation criteria and indicators of environmental vibration of rail transit are summarized.(2)Based on the finite element model,the propagation law of vibration in buildings is analyzed:vibration fluctuates with the change of building floors,with the increase of floors,it increases gradually and then decreases,after reaching 22 floors,it enlarges to a certain extent,the maximum acceleration of vibration occurs at the top of the building;the energy distribution of the vibration spectrum is basically the same,the vibration energy mainly distributes in the vicinity of 20 to 30 Hz,and there is only one main peak value.With the increase of building floors,the change trend of the maximum frequency division magnitude of each floor increases first,then decreases and then increases,but the overall difference is not significant,the change range is about 4.47%.(3)Through the numerical simulation method,the vibration isolation principle of empty ditch and filling ditch is analyzed,and the influence of the depth(h=5、10.、15m)and width(w=0.5、1.0、1.5m)of the air ditch and filling ditch on the vibration isolation effect is emphatically analyzed.The effect of vibration isolation can be achieved by using the empty ditch and the filling ditch.The effect of the depth is more significant to the vibration isolation effect,and the vibration isolation effect varies with the depth.The change is nonlinear growth trend,while the width change has little effect on the vibration isolation effect.(4)By comparing the vibration isolation effect of the empty ditch and filling ditch,it is found that when the depth is h=5m and h=10m,there is no obvious difference in vibration isolation effect between empty trench and filling ditch.When h=\5m,the vibration isolation effect of the empty ditch is obviously better than the filling ditch,but with the increase of depth,the stability of empty ditch will be weakened.In actual engineering,the selection of vibration isolation measures should be considered comprehensively according to factors such as vibration isolation effect,enforceability and economic conditions.