| Underground rail transit has been developed rapidly in the urban construction for its characteristics of safety, fast, punctuality, convenience, comfort and large transportation. However, people pay more and more attention to the environmental vibration problem induced by the operation of metro. At present, environment problem induced by the operation of several new lines become extremely serious, there have been a lot of complaints and collective petitions from residents along the route and noise of some lines induced by vibration exceeds standard seriously, vibration of the building exceeds standard, which disturbs residents's rest and working.To solve above-mentioned problems, relying on the National Natural Science Foundation of China (50848046,50538010), the combination method of theoretical analysis, field testing and finite element simulation was adopted, the vibration induced by subway operation was researched deeply and methods that was based on the transfer function and could predict building vibration induced by subway operation was proposed. The content and results are as follows.1. China's first automatic drop hammer excitation device which can be applied on the track and ground was invented by author, which then applied the national patent. Making use of the 10m depth tunnel of Lab. of Track Vibration abatement & Control of Beijing Jiaotong University, the vibration transfer function including the transfer function amplitude and phrase, and coherence function of the ground layers and buildings were got by measurement and the change law of ground layers'transfer function with different horizontal distance and the effect that the different building structures have on buildings' transfer function were discussed.2. The three-dimensional finite element model of laboratory was built, the accuracy of three-dimensional finite element model was tested by making use of the test results, and then the finite element model was expanded to study the effect that different layers and different tunnel depth have on the tunnel ground vibration attenuation. The following conclusions can be drawn:(1) The vibration response time history decreases with the increase of the depth of the tunnel and the horizontal distance from the track, and the time history peak reaches the maximum in the 20m above vibration source and attenuates most rapidly; (2) Ground single-frequency vibration is a wavy-type attenuation, the magnitude and attenuation law of different frequency vibration is different, but the attenuation curves of adjacent frequency vibration are similar; (3) Different layers' properties have a significant effect on the attenuation of speed, especially on the attenuation of the displacement.3. Prediction method of vibration within the buildings based on pulse experiment is proposed, which has advantages of high efficiency, wide frequency and high accuracy. Test results indicate that:adopting the transfer function method to predict the metro train-induced environmental vibration response is practicable, and the prediction is accurate. This method has the scientific guidance for designers to select the appropriate type of vibration attenuation track and railway lines.4. The vibration dynamic tests were carried out on the ladder track system and steel spring floating slab track system in the Lab. of Track Vibration abatement & Control of Beijing Jiaotong University. The vibration mode (natural frequency, mode shape and damping) of the ladder track and steel spring floating slab track were got, The first modal frequency of ladder track is 31 Hz and the first modal frequency of steel spring floating slab track is 9 Hz; The vibration properties of the two tracks were analyzed by making use of the hammer hit test and the vibration transfer function and transmission loss of the two tracks were got. |
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