Research On Environmental Vibration By High-shpeed Railway And Measures Of Vibration Isolation

With the increase of railway speed, axle load, road network density and traffic density, the railway transportation has aggravated the pollution to the environment. The pollution to the environment due to the modern railway transportation lies in railway noise and environment vibration transmitted by ground. During the operation of the vehicle, the dynamic load caused by moving axle load and track irregularity leads the vehicle and track structure to vibrate. The vibration of the track structure transmitted from track to ground generates the vibration wave. The influence of the vibration on the residents around the railway, neighboring constructions, underground utilities and precise instruments can’t be ignored. Therefore it is very meaningful and of applied value to analyze the environment vibration caused by high-speed railway as well as how to reduce the vibration.Based on the existing research, the finite element method was applied to establish the vehicle-track-subgrade vertical model and the track-subgrade-ground two-dimensional model for dynamic analysis respectively, thus analyzing the vibration performance of the double block ballastless track with the vehicle at the speed of250km/h、300km/h and350km/h. The isolation trench and concrete underground diaphragm wall were considered as the vibration isolation measures in the research. The influence of the burial depth, thickness and setting position of isolation trench and concrete underground diaphragm wall on the vibration isolation effect were analyzed. The results show that:(1)with no measures of vibration isolation or the isolation trench or concrete underground diaphragm wall, the the supracrustal vibration has little change even can be ignores when the speed ranges from250km/h to350km/h.(2) Within the range of50m from the center line of the track, the supracrustal vibration limit exceeds80dB according to the City Regional Environment Vibration Standard.(3) The supracrustal vibration decreases with the increasing distance from the center line of the track. The vibration magnitude that is larger than20Hz is damping rapidly, while that of lower than20Hz is damping slowly.(4) The isolation trench has a prominent effect on the supracrustal vibration isolation. Under the calculated condition in the paper, the vibration magnitude of the calculated point representing the ground after the isolation trench is about lOdB lower than that without the isolation trench. When the buried depth of the isolation trench with the thickness of0.5m measuring15m (d=15m) from the center line of the track (w=0.5m) is12m (h=12m), the supracustal vibration after the isolation trench can basically meet the requirement of80dB according to the City Regional Environment Vibration Standard.(5) The buried depth of the isolation trench has a significant influence on the supracrustal vibration, while the setting position and thickness change of the isolation has a little influence on that.(6)The concrete underground diaphragm wall cannot benefit for the supracrustal vibration. The calculated point near the concrete underground diaphragm wall has a good effect of vibration isolation, while that far from the concrete underground diaphragm wall has a bad one.(7) The buried depth, setting position and thickness of the concrete underground diaphragm wall have a little influence on the supracrustal vibration isolation.Finally, the vibration isolation effect of the isolation trench, concrete underground diaphragm wall and flyash-filled trench is compared and analyzed under the same conditions. It shows that the vibration isolation effect of the isolation trench is the best, while that of flyash-filled trench is worse. And the worst one is the concrete underground diaphragm wall.