Prediction Of Acoustic Environmental Impact By Urban Rail Transit And Study On Noise Reduction Measures

In recent years, with the rapid development of urban rail transit in China, the traffic noise has inevitably become urban environment pollution, making adverse effects on the residents along. Taking Chengdu Metro Line 5 for example, this paper predicts the environmental noise of elevated line, carries on the analysis and evaluation of the effects of noise, and proposes prevention and control measures to solve noise pollution.Firstly, this paper analyzes the elevated railway noise prediction model and research method at home and abroad. It identifies each forecasting parameter by the design of Chengdu Metro Line 5, and proves that the prediction results are correct and reliable by a large number of measured data in a similar project. Based on the obtained prediction results, further research is done on the distribution rule of which the train operation acoustic propagation is different in horizontal distance and vertical height. This provides a theoretical basis for the prevention and management of traffic noise on sound environment sensitive points on both sides of the track.Then, by the noise prediction model, combined with field investigation and monitoring of environmental background values, the Equivalent grades of environmental noise in some typical sensitive points which are in the viaduct section of Chengdu Metro Line 5, are calculated in different periods of day and night respectively. The influence degree of train noise sense on both sides of the line sensitive target is analyzed and evaluated. According to different requirements of different functional area in acoustic environment, space contour line is calculated, which reflects the noise effect on both sides of the target elevated section. And the corresponding standard distance is predicted, providing a reference for the land using and planning departments along the line.Finally, according to the forming principle and transmission characteristics of noise, the paper describes the main results to reduce the noise impact of urban rail transit in planning layout, the noise source, route of transmission and reception sound matter. In order to reduce the noise influence of elevated bridge, bridge structure parameters are changed quantitatively. The result is that bridge noise intensity increases with the increasing of roughness and reduces with increase of damping. On this basis, the corresponding measures and suggestions for prevention and control of noise pollution are proposed, to ensure the sound environment of rail traffic on both sides of environmental sensitive targets to meet the requirements of the national standard limit value.