声屏障插入损失影响因素及降噪机理研究

摘要

为了分析高速铁路户外噪声的降噪机理和降噪效果,采用二维边界元法建立高架桥铁路声屏障噪声预测模型,分析不同因素对降噪性能的影响.基于试验结果,对有、无声屏障时的声场分布、场点声压时间历程及频谱特性、插入损失特性及其与速度的线性拟合关系进行探讨,分析声场分布特征和速度对降噪效果的影响.根据场点主要频率,采用边界元法和高速铁路户外噪声仿真模型对吸声系数、声屏障厚度、高度、倾角及面板结构形式等影响因素的降噪机理和降噪效果进行调查分析.分析中,分别考虑以上因素对声场分布、场点声压级及频率特性变化规律的影响.研究结果表明,声屏障采用鼻型结构、外倾30°时的降噪效果最好.%The two-dimension (2D) boundary element method (BEM) was used to develop a noise prediction model for railway noise barrier in order to make clear the noise reduction mechanism and effect of the sound barrier.In-depth discussions about the sound field distribution were conducted when there had barrier or no barrier based on test results.The time history of field points and their frequency characteristics, the characteristic of insertion loss and its linear fitting relationship with speed were discussed.The acoustic field distribution characteristics and noise reduction effect was analyzed.According to the main frequencies of field points, the boundary element method and the outdoor noise simulation model of high-speed railway were used to investigate noise reduction mechanism and effect of some factors, such as absorption coefficient, thickness, height, dip angle and structural style of barrier.The change of sound field distribution, sound pressure and its frequency characteristic were discussed.Results show that the noise reduction effect of nose-barrier and inclination outward 30° is best.