| With the continuous expansion of the railway transportation network in mountainous area and the continuous improvement of train speed,the noise impact of railway on the acoustic environment sensitive areas has gradually attracted widespread attention.Especially in the mountainous area with the diverse and fragile acoustic environment sensitive areas,the control of railway noise is stricter.The noise impact of the railway on the acoustic environment sensitive areas is closely related to the location of the line scheme.Therefore,at the stage of railway line scheme design and comparison,it is necessary to construct a low-noise line scheme optimization method from the perspective of reducing the noise impact,and reasonably determine the line scheme that has the least impact on the acoustic environment sensitive areas,so as to effectively reduce the noise pollution of the railway to the surrounding acoustic environment sensitive areas.For this reason,this thesis mainly conducted research from the following four aspects:(1)Through a systematic summary analysis of the evaluation indicators,generation mechanism,sound source characteristics,propagation attenuation characteristics,impact characteristics and prevention measures of railway noise,the equivalent continuous Aweighted sound pressure level and the maximum A-weighted sound pressure level were simultaneously used as the noise impact evaluation indicators of the acoustic environment sensitive areas in mountainous area.And the wheel/rail noise was determined as the basis for prediction and calculation of railway noise impact value.(2)According to the vibration characteristics of the wheel/rail system,the multi-body dynamics theory and the finite element method were used to establish the vehicle-track rigidflexible coupling dynamics model with the help of UM and ANSYS software.On this basis,the wheel/rail noise radiation calculation model was correspondingly improved,and through mature theoretical calculation models and on-site measured data,the established calculation model was double-verified in terms of the wheel/rail noise spectrum characteristics and the maximum A-weighted sound pressure level of railway noise.(3)Combined with the vehicle-track rigid-flexible coupling dynamics model and the wheel/rail noise radiation calculation improved model,this thesis simulated and analyzed the influence law of linear parameters and propagation distance on the maximum A-weighted sound pressure level of the wheel/rail noise under the condition of 200km/h～350km/h speed during the passage of vehicle.And according to the simulation results,the relationship function expressions between the linear parameters of each line and the maximum A-weighted sound pressure level of the wheel/rail noise were established.(4)According to the relationship function expressions between the linear parameters and the maximum A-weighted sound pressure level of the wheel/rail noise and the contribution ratio of the wheel/rail noise,the calculation formulas for the maximum A-weighted sound pressure level of railway noise under different linear parameters were constructed.Combined with the type of acoustic environment sensitive areas in mountainous area and corresponding noise control requirements,the relevant railway noise impact assessment standards have been determined.And the railway noise limit maps,impact value maps and the over-limit maps of acoustic environment sensitive areas around railway were established by GIS,then the comprehensive unit noise optimization indicator was proposed,the low-noise line scheme optimization method was established,and the feasibility of the method was analyzed with an engineering example. |
