基于逆边界元法的轨道交通桥梁全空间低频噪声研究

The structure-borne low-frequency noise radiated from urban rail transit bridges is harmful to human health. The forward prediction model is hardly to simulate the sound pressures of all the field points around the bridge due to the uncertainty of related parameters in the numerical model. In this project, a numerical model combining the inverse boundary element method (BEM) and the measured results of a minority of field points is proposed to reconstruct the sound field, with high accuracy and efficiency. First, the forward prediction model is used to simulate the bridge noise, and the simulated results of a few field points are used to reconstruct the sound field using inverse BEM and modal acoustic transfer vectors. Second, the accuracy of the inverse BEM is verified by comparing sound pressures obtained using inverse BEM with the results calculated using forward prediction. The selection principle of the regularization and related parameters in the inverse analysis is also studied. Third, field measurements are conducted to further validate the accuracy of the inverse BEM. Finally, the proposed method is used to investigate the spatial distribution and propagation of the structure-borne noise radiated from the U-shaped girder bridge and box girder bridge, respectively. The results of this project can lay a solid theoretical foundation for reduction of bridge vibration and associated noise radiation, which has a promising engineering value.

列车通过时引起的轨道交通桥梁结构低频噪声对人体的危害很大，而数值计算预测模型中参数的不确定性使得正向计算方法很难准确预测桥梁附近所有场点的声压值。为此，本课题提出一种基于逆声学边界元技术和少数测点实测值来重构全空间桥梁噪声的预测模型，以提高结构噪声的预测精度和效率。本项目拟通过：（1）提出基于声模态传递向量的逆边界元声学反演模型，然后选取正向预测模型中的一些场点作为虚拟测点重构桥梁结构噪声；（2）通过正向预测结果与反演结果的对比来探究逆声学模型的精度和适用性，明确正则化技术和相关参数的选取原则；（3）通过现场实测进一步验证声学反演方法的准确性，进而采用逆声学模型对轨道交通U梁和箱梁的全空间噪声分布特性及传播规律进行系统研究。本课题的研究成果将为桥梁减振降噪提供理论支撑，具有明确的工程应用价值。

列车通过时引起的轨道交通桥梁结构低频噪声对人体的危害很大，而数值计算预测模型中参数的不确定性使得正向计算方法很难准确预测桥梁附近所有场点的声压值。为此，本项目提出一种基于逆声学边界元技术和少数测点实测值来重构全空间桥梁噪声的预测模型，以提高结构噪声的预测精度和效率。主要包括：（1）基于声模态传递向量的逆边界元声学反演模型，通过选取正向预测模型中的一些场点作为虚拟测点来重构桥梁结构噪声；（2）通过正向预测结果与反演结果的对比探究了逆声学模型的精度和适用性，明确了正则化技术和相关参数的选取原则；（3）通过现场实测验证了声学反演方法的准确性，并对轨道交通U梁和箱梁结构的全空间噪声分布特性及传播规律进行了系统研究，厘清了钢轨噪声与桥梁噪声在空间不同位置的占比大小。研究表明仅需要4~5个测点的声压测试结果和声模态传递向量即可快速准确实现桥梁全空间的声场重构，规避了正向预测模型的参数不确定性问题，提高了全空间声场的预测精度，研究成果可进一步完善轨道交通桥梁设计分析方法，为桥梁减振降噪措施的选取提供理论支撑。