西宁市道路绿地及乔木树种的降噪效应

Study on Traffic Noise Attenuation Provided by Street Green Area and Arbor Trees in Xining

对西宁市3种道路绿地和12种道路绿化树种降噪效果的测定表明,西宁市道路绿化中采用乔木、灌木和地被植物组成高低错落的绿地能使交通噪声降低9.0dB,比用乔木树种组成乔木绿地降噪量高44.37%;道路绿地的降噪量与绿地宽度以三次多项式拟合度最高;3种绿地即乔+灌+地被、乔+灌和乔木降噪量日变化呈凸峰线;西宁市道路绿地的平均日降噪量为7.37dB。12种绿化树种降噪量从大到小依次为河北杨、小叶杨、毛白杨、欧洲白榆、新疆杨、旱柳、白榆、国槐、青杨、白蜡、油松、云杉,叶面粗糙且被毛的树种具有较好的降噪效果。车流量、树种、树冠疏透度、叶部特征、树高、枝下高和冠幅7个因子与树种的降噪量均具有相关性,其中,车流量、树种种类、疏透度和叶部特征为主要因子。

Determine the effects of traffic noise attenuation by 3 types of street green spaces and 12 types of arbor tree in Xining,The results showed： ①The street green area which were compositioned with arbor、brush and ground cover plants in Xining provided the effects of traffic noise attenuation to about 9.0 dB,The noise reduction was higher 44.37% than the arbor tree’s; The noise reduction of the street green area was fitted with the green area width with a best fitted cubic polynomial mathematic model; the dair changes in 3 types of street green spaces（trees-shrubs-ground cover plant、trees-shrubs and trees）of noise reduction appeared convex peak line,the average of the dair noise reduction in Xining was 7.37 dB. ②The noise reduction of 12 types of arbor tree was arrangemented from large to small：Populus hopeiensis、Poplus minhoensis、Poplus tomentosa、Ulmus laevis、Populus alba、Salix matsudana U. pumila、Sophora japonica、Poplus cathayana、Fraxinus chinensis、Pinus tabulaeformis.and Picea crassifolia,the effects noise attenuation ofthe trees which it’s leaves were coarse and covered with villus were better than other’s. ③7 types of factor with traffic、 trees、 porosity、 leaf characteristics、 tree height、 branch height and crown had correlation with the noise reduction of arbor trees.the pivotal factors were traffic、 tree species、porosity and leaf characteristics, A combination of all these factors influenced the noise attenuation effectiveness of street green spaces.