【作者】 殷利华；

【导师】 万敏；

【作者基本信息】 华中科技大学 ， 城市规划与设计， 2012， 博士

【摘要】 城市高架桥是现代城市在有限道路用地内解决拥堵的必然产物,它给城市交通带来畅达的同时,也产生了环境、经济、景观等负面影响并衍生出一定的桥下消极空问。桥阴绿地是缓解这一矛盾的有效方式之一,但桥体遮盖引起的光照不足、雨水缺乏等环境问题以及交通污染等给其景观利用带来不利影响。本文利用Ecotect Analysis软件进行高架桥下自然光环境模拟,分析桥阴自然光环境规律,用光合仪测试桥阴植物光合特性,探讨桥阴绿地景观的积极策略,结果表明：(1)高架桥桥体走向、桥下空间高宽比B值、桥体分离缝宽度对桥阴绿地自然采光的影响明显,且存在相关变化规律：较好走向桥体的桥阴下,植物生长有效期间的平均光合有效辐射PAR分布均匀度、平均日照时数均明显优于较差走向的高架桥下,但高PAR (PAR≥3MJ/m2·d)面积比、高日照时数(桥阴日照时数≥50%全日照时数)面积比都不及较差走向的桥体采光面。随着桥下B值增大,桥阴PAR和日照时数均呈不同比例的线性增长关系,通过回归分析可找出其临界B值：减少低PAR(PAR<1 MJ/m2·d)面积比的临界B值,较好走向桥下为0.367,较差走向桥下为0.497；减少低日照时数(桥阴日照时数<20%全日照时数)面积比的临界B值,较好走向桥下为0.43,较差走向桥下为1.68。桥体分离缝宽达2m时,武汉城市高架桥下常见桥下净空B值为0.231的跨间低PAR面积消失；缝宽4m时,桥阴低日照时数面积比接近于0。(2)武汉市桥阴绿地植物的耐阴能力按植物光饱和点、补偿点分为3大类6小类。利用LI-6400XT(美国)光合仪对武汉市八角金盘(Fatsiajaponica)等共29种桥阴植物进行光-光响应曲线的测定,计算出其光合补偿点、光饱和点等光合特性参数,聚类得到这些植物的耐阴类别。在结合调研和文献研究基础上,提出武汉市桥阴共98种推荐绿化植物名录,为丰富武汉市桥阴绿化品种提供参考。(3)适生区植物配置对应自然光环境分布存在一定规律：以桥阴绿地等PAR线为参考,桥下B值在0.3及以上时,等PAR线与桥边线平行,且呈桥体中轴线两边对称分布,较好走向的桥阴中间适合最耐阴Ⅰ-A类植物栽种宽度约占桥宽40%,Ⅰ-B、Ⅱ-A、Ⅱ-B类植物占桥宽42%,部分Ⅲ类占桥体两边共18%桥宽范围；较差走向的桥阴下PAR两边分布不均,Ⅰ-A类植物栽种宽度约占桥宽60%,且类别、栽种面积都比较好走向少。Ⅱ类、Ⅲ类植物同时还受日照时数影响：两个典型走向的桥阴下Ⅰ、Ⅱ类种植宽度都不同程度的增加、Ⅲ类栽种区域减少或消失。叠加两个光环境指标的综合作用,得到适应桥阴自然光环境的植物配置指引图。(4)非适生区具相对概念,其面积大小与B值呈反比例关系。本文倡导利用铺装、美化设施、文化展示、活动场地等策略处理,特别倡导在引桥端等位置营建桥面雨水收集、净化及浇灌系统,充分发挥桥阴绿地景观的综合效益。本文最后对尚未深入并希望同行关注的3个问题进行了展望：(1)慎建城市高架桥,同时合理对待已建高架桥,注重桥阴空间积极利用并发挥其综合效益；(2)郊区段高架桥下开展与两边绿地一体化的特色都市农业活动；(3)思考桥身一体化的被动式桥阴导入阳光的反光板技术,集桥面雨水收集、净化、绿地灌溉及市政补水于一体的桥阴绿地浇灌系统技术。更多还原

【Abstract】 Urban viaducts are used for solving serious traffic problems in modern cities, but they have brought negative impacts on urban environment, economy and landscape, which produce some passive spaces under viaducts. The green space is one of effective ways to solve this problem, but the green plants can’t grow healthy because of the inadequate lighting, lack of rainwater, traffic pollution and other issues under viaducts.This paper used the Ecotect Analysis software (Inc. UK) to analyze the daylight environment rules under viaducts. It tested the plants photosynthetic characteristic under viaducts, and then discussed the actively strategies of shaded green space landscape. The results indicated that:(1) There are 3 factors of the viaducts’ construction, such as the viaducts’ tending towards, the ratio of width and tallness of the space under viaduct (that is B value) and the separated slot width of viaducts, have great impact on the natural light environment under viaducts, and their orderliness were as followed.The average photosynthetic actively radiation (PAR) and the average sunshine hours in the spaces under the fine tending towards viaducts are much higher than the disbennifit viaducts, but the higher PAR(PAR≥3MJ/m2·d) area ratio and the high sunshine hours(sunshine hours≥50% full sunshine hours) area ratio under the fine are worse than the disbennifit ones. The PAR and the sunshine hours are linearity increasing in different ratio with the B argument under viaduct. It finds the critical B values by regression analysis that is, the critical value of B for decreasing the low PAR (<1 MJ/m2·d)area ratio: 0.367 for the fine tending towards viaducts,0.497 for the disbennifit tending towards viaducts. The critical value of B for decreasing the low sunshine hours (<1 MJ/m2·d) area ratio:0.43 for the fine tending towards viaducts,1.68 for the disbennifit tending towards viaducts. The lower PAR area disappeared when the viaduct separation width up to 2m, and the B value is 0.231; the lower sunshine hours area ratio close to 0 when the separation width up to 4m.(2) This paper divideed the shaded sorts of plants under viaducts in Wuhan city into 6 small types and 3 big types based on their light saturation points (LSP) and light compensation points (LCP).This paper tested 29 species of plants’ Photosynthetic rates-photosynthetic photo flux density (Pn-PPFD) under viaducts in Wuhan city with LI-6400XT photosynthesis system (Inc. USA), figured out the plants’LSP and the LCP, and clustering these photosynthetic characteristics into 6 small types and 3 big types. This paper put forward 98 species of plants to adapt to the shade spaces under viaduct in Wuhan based on research and literatures, and it can provide references to enrich the plant species under Wuhan viaducts.(3) There are some rules for planting in adaptive survival areas on natural light environment under viaducts:The equal PAR lines parallel with the viaduct edges when the B value exceeds 0.3, and the best tolerant shaded plants,Ⅰ-A type plants can be planted 40 % width under the fine tending towards viaducts, theⅠ-B、Ⅱ-A、Ⅱ-B types 42%, a part ofⅢtype at 18% width of viaducts. However, the equal PAR lines distributing under the disbennifit tending towards viaducts are not uniformity, the ratio of width forⅠ-A is 60%, and other types are less than the fine viaducts.TheⅡ,Ⅲtype plants are also affected by sunshine hours, as a result, theⅠ,Ⅱtypes planting area are increasing and theⅢtype planting area is decreasing or disappearing under the two typical different tending toward viaducts. Calculated the two factors of natural light environment integration effect, we found the planting direct plan adapt to natural light environment under urban viaducts.(4) Non-adaptive survival areas have inverse proportion relationship with the B value under viaducts. This paper made suggestions such as pavement, prettification establishment, activity grounds to deal with this area, in particular, it proposed that we can construct a system of collecting, decontaminating the viaduct surface rainwater, and irrigating the shade plants, which maybe bring into play the landscape best benefit.Finally, this paper expected 3 issues which yet not be penetrated into and it expected be attention by craft brothers:1) be cautious of building viaducts, and treat the existent viaducts in reason, and we should exert the active use of the shade spaces under viaducts. Spaces under suburb viaducts may be used the urban agriculture places with green space on both sides,3) it may consider the sunshine reflecting boards technique on viaducts, the system of collecting, decontaminating the viaduct surface rainwater, and irrigating the shade plants.更多还原