高速铁路桥梁全封闭声屏障结构噪声特性

开展了高速铁路桥梁和桥梁-全封闭声屏障典型结构断面的振动和噪声测试，建立了高速铁路桥梁-全封闭声屏障系统结构噪声的快速多极边界元法(FMBEM)数值预测模型，深入分析了板件的车致振动与结构噪声辐射的相关性和时频特性，并以此验证了FMBEM数值预测模型求解结构噪声的准确性；对比分析了有、无全封闭声屏障工况下32 m简支箱形梁桥结构噪声的空间和频域分布特性，并比较了FEBEM与边界元法(BEM)的计算效率。分析结果表明：桥梁-全封闭声屏障系统板件的振动与噪声的频谱分布规律基本一致；受全封闭声屏障隔声作用和梁体遮蔽作用的影响，距箱梁底板表面0.3 m处测得的噪声信号基本反映了底板的结构噪声特性，其余测点则不同程度地受到其他板件或轮轨系统辐射噪声的影响；计算与实测噪声的幅频特性吻合较好，峰值处计算误差在1.5 dB以内；全封闭声屏障的安装导致桥梁板件的振动和结构噪声均减小，也改变了桥梁周围的声场分布特性，桥梁板件表面场点的总声压级降低了0.8 dB，梁体下方地面场点总声压级增大了4.1~9.4 dB；梁体斜上方场点总声压级增大了9.6~18.1 dB，桥梁-全封闭声屏障结构顶部局部区域的结构噪声比无声屏障的桥梁大12.4 dB以上；FMBEM计算耗时为传统BEM的1/3，计算更为高效。

Structure-borne noise characteristics of fully-enclosed sound barriers on high-speed railway bridges

A test was conducted on the vibration and noise of typical structural cross-sections of high-speed railway bridges and bridge-fully-enclosed sound barriers. A numerical model was established based on the fast multipole boundary element method (FMBEM) for predicting the structure-borne noise of an high-speed railway bridge-fully-enclosed sound barrier system. The time-frequency characteristics of train-induced vibration and the structure-borne noise radiation of component plates and their correlations were analyzed in detail, and the accuracy of FMBEM numerical prediction model for calculating the structure-borne noise was verified. The spatial and frequency domain distribution characteristics of structure-borne noise of a 32 m simply supported box girder bridge with and without fully-enclosed sound barriers were compared and analyzed, and the calculation efficiencies of FMBEM and boundary element method (BEM) were compared. Analysis results indicate that the spectral distribution of component plate vibrations of the bridge-fully-enclosed sound barrier system is consistent with that of the structure-borne noise. Influenced by the sound insulation effect of fully-enclosed sound barriers and the shielding effect of girders, the noise signals measured at 0.3 m from the bottom plate of the box girder reflect the structure-borne noise characteristics of bottom plate. Additionally, other measurement points are influenced to varying degrees by the noise radiated from other component plates or the wheel-rail system. The amplitude-frequency characteristics of the simulated and measured noise are consistent with each other, and the simulation error of peak value is within 1.5 dB. The installation of fully-enclosed sound barriers reduces the vibration and structure-borne noise of bridge plates, and alters the distribution characteristics of sound field around the bridge. The overall sound pressure level of field points on the bridge plate surfaces decreases by 0.8 dB, whereas those under the girder and diagonally above the girder increase by 4.1-9.4 dB and 9.6-18.1 dB, respectively. The structure-borne noise at certain points above the bridge-fully-enclosed sound barrier system is approximately 12.4 dB greater than that of the bridge without sound barriers. Furthermore, the calculation time of FMBEM is 1/3 that of the traditional BEM, indicating the improved efficiency of FMBEM. 3 tabs, 16 figs, 30 refs.