【作者】 袁玲；

【导师】 王选仓；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2009， 博士

【摘要】 公路建设的快速发展对公路所经地区的经济起着重要作用的同时，行驶在公路上的车辆向两侧辐射的噪声也给沿线居民造成了严重的声环境污染。在声敏感点和道路之间设置障碍物是控制噪声传播的主要方法，林带作为障碍物，当达到一定宽度，可有效地降低噪声。然而，目前林带降噪机理尚不完全清楚．一方面，在噪声评价中，由于现有的林带声衰减量表达式过于简化，不能反映林带实际特征，因此，噪声预测结果常产生较大误差；另一方面，由于缺乏定量依据，林带降噪也难以应用到实际公路降噪工程中。为此，本文从声学基本原理出发，对林带声衰减效果、林带声衰减机理、林带声衰减量、林带降噪设计进行系统的研究。本文主要研究内容如下：(1)林带声衰减效果及影响因素研究。运用HS6288B型噪声频谱分析仪分别在夏季、冬季现场监测高速公路两侧不同配置类型的林带前、后噪声水平。分析林带声衰减效果及林带噪声衰减影响因素，发现林带声衰减量随着宽度、郁闭度和高度增加呈非线性增加；比较了不同季节林带的降噪效果，30m宽常绿林带冬、夏季可有效地降低交通噪声能量。(2)林带衰减声能机理研究。通过分析林带声能衰减的频谱曲线和植物内部显微结构，发现植物组织结构不同声能衰减的频率分布不同。茎的共振吸声结构主要影响500Hz以下频段噪声衰减量；叶片的多孔吸声结构主要影响500Hz-8kHz频段噪声衰减量。林带的散射作用主要影响高频区域声衰减量。(3)林带声衰减量公式研究。基于林带吸声及散射机理的分析，从声波通过林带传播原理推导出林带声衰减量计算公式，建立的林带声衰减量计算公式综合考虑了林带宽度、高度、灌幅、种植间距、最低分枝高度、林带前端距路中心线距离、林带种类和季节等因素的影响，将公式应用于公路交通噪声预测模式中，经与林带后监测点夏秋季、冬季噪声实测值比较，其噪声预测精度均明显优于同类公式，因此，推荐本研究公式为噪声传播通过不同类型林带声衰减量的预测公式。(4)林带降噪应用研究。对林带宽度、高度、长度等降噪参数的设计进行了研究，给出了林带降噪设计一般原则及适用条件，将公路林带降噪设计理论应用到实际工程，对吉珲高速公路林带降噪设计实施方案的降噪效果进行了预测，从而达到精确控制林带后噪声水平的目的，指导实际工程的降噪设计。(5)降噪林带的设计与景观生态的协调性研究。将林带形态、色彩等美学特性、公路交通安全、生物多样性，边坡稳定性、环境保护、病虫害防治等理论综合应用到公路林带的设计中，达到营造舒适、安全的行车环境、改善景观和生态环境的目的。更多还原

【Abstract】 The fast development of highways promoteed tremendously the economics of the passing area. However, serious acoustic environmental pollution to the nearby habitants was brought in by the noise emitted from the vehicles also. The dominant methods to control the noise’s transmission were setting up acoustic obstacles between the sensor points and the highway. As acoustic obstacle, the tree belt with sufficient width could reduce the noise effectively. However, the current mechanism of tree belt reduction noise was not yet entirely clear. On the one hand, in the noise evaluation, because of the existing tree belt sound attenuation expression was too simplified to reflect the actual characteristics of tree belt, the noise prediction results often had a greater error. On the other hand, because of the lack of quantitative basis, it was difficult to applied tree belt to the actual road noise reduction project. In this paper, based on fundamental acoustic principles, a systematic study of tree belts’ noise-reducing effect, mechanism, quantification and design were executed. The main research contents of the present wok were as follows:1. Acoustic attenuation effects and its influencing factors of tree belt. Noise spectral analyzer, HS6288B, was used to monitor in situ the noise levels along a highway before and after various kinds of tree belts, in summer and in winter respectively. By analyzing the acoustic attenuation effects and influential factors, it is found in this thesis that the attenuation amount increases nonlinearly with the width, the crown density and the height of the tree belts. By comparing the attenuation effects of the tree belts in different seasons, it is found that evergreen tree belts of 30m wide could effectively reduce the traffic noise energy both in the winter and in the summer.2. Mechanism of attenuation sound energy of tree belt. In this thesis the spectral curves of acoustic energy attenuation by tree belts were analyzed and correlated to the internal microscopic structures of the plants. It is found that different tissue structures in the plants have varied acoustic attenuation frequency. The resonance sound-absorbing structures in the stem attenuate mainly the noise with frequency below 500Hz. While the multi-pore sound-absorbing structures in leaves attenuate mainly the noise from 500Hz to 8kHz. The sound-scattering effect of tree belts contribute to the attenuation at even higher frequency.3. Sound attenuation formula of tree belt. Based on the analysis to the acoustic absorbing and scattering mechanisms of tree belts, the formula to calculate the noise-reduction by tree belt was deduced in this thesis according to the transmission principles of acoustic wave through forest. In this formula, various kinds of influential factors, such as the tree belt’s total width and height, the diameter of a tree crown, plant intervals, height of lowest branches, distance between the tree belt and the central line of the highway, and plant species and season, etc, had been considered comprehensively. Applying this formula into the traffic noise prediction models, it is found that the predicting accuracy is apparently superior to other formulas of the similar kind by comparing the real noise test results in summer and winter. Based on this, the author recommends using this formula as the official predicting formula to calculate the attenuation amounts of highway traffic noise transmitted through tree belts of various kinds.4. Design and application of noise reduction of tree belt, by researching the effects of many noise-reducing parameters like tree belts’ width, height and length, the general principles of noise-reducing design and related applying condition were provided in this thesis. The noise-reducing design of tree belt was applied to practical engineering. According to the results, the noise-reducing effects of the tree belt designed for Ji-Hun highway had been well predicted, and achieving the purpose of precise control to the noise levels behind the tree belts. Thus providing a good guidance to the noise-reducing design of the practical projects.5. Coordination of tree belt and landscape ecology. To build a comfortable, safe driving environment and improve the landscape and ecology along highway, The theory and strategy of a aesthetics characteras of tree belts such as shape and color, traffic safety, biodiversity, slope stability, environmental protection and pest control were applied to the design of tree belt along highway.更多还原