北方城市风道体系构建模式及生态空间协同规划方法研究—以西安为例

Urban environmental problems in our country have become increasingly prominent in recent years, especially in northern region China, the urban Heat Island Effect, sand and dust weather, as well as the air smog, are becoming a more normality. In this context, Xi'an is selected as a typical case and definite object at the service of the research, which is mainly about the construction method of ventilation corridor system in northern cities. To be specific, this research project is “Built Utility-Oriented”, referencing the advanced experience of wind path (air passage) planning both at home and abroad, on the basis of mastering the principles, which include the forming, transferring and attenuation of wind, through wide range of monitoring and field research, to summarize the characteristics of wind environment and regular pattern of air flow in Xi'an. At the same time, relying on the urban open space’s current status and ecological planning mode, build the urban ventilation corridor system from five aspects, which are grading, classification, partition, time-division and strategy differentiating. Establish evaluation indicators of ventilation performance in built-up area and comprehensive ecological benefit of urban underlying surface, simulate the situations of urban ventilation and surface heat change, with the help of computer software. Then setting the construction standard of urban ventilation corridor with a multidisciplinary perspective, and taking Xi' an as the pilot city, in line with the principles of “optimizing the old city, controlling the new district, generally creating and locally dredging”, in order to propose in detail the planning conditions of urban land use, architectural design criteria and green space layout mode of each wind source zone, wind offtake zone and wind path zone. Finally generalizing the collaborative construction planning theory and method of urban ventilation corridor combined with ecological open space system, and making "Wind Path plus" concept as the implementation approach, to simultaneously endow the urban wind path’s development process with more functions of serving people’ daily life.

近年来我国城市环境问题日益凸显，尤其是北方地区城市的热岛效应、沙尘天气与空气雾霾更加成为常态，在此背景下选取西安市为对象，研究北方城市的通风廊道建设方法。具体以风道建成效用为导向，借鉴国内外风道规划的先进经验，在掌握风的形成、输送与衰减等原理的基础上，通过广泛监测与实地调研，总结西安城市风环境特征与行风规律；并以城市开敞空间为依托，从分级、分类、分区、分时、分策等五方面构建城市风道体系；制定城市建成区通风性能及下垫面综合生态效益评价指标，借助计算机软件进行城区通风与地表热量变化情况模拟；以多学科视角制定城市风道建设标准，并以西安为试点，本着“旧城优化、新区控制、总体打造、局部疏导”的原则，提出各风源、风口、风廊地带的城市用地规划条件、建筑设计准则和绿地布局模式；归纳出城市风道与开敞空间的协同规划理论方法，并以“风道+”理念作为实施途径，为城市风道建设赋予更多的人居生活服务功能。

针对我国北方地区近年来常受气候环境问题侵扰的代表大城市——西安，首先对其所在省域及市域的气候特点与风象情况做以掌握与总结，明确市区主导风向的产生背景及基本运行规律；进而以西安主城区为研究范围，梳理以往规划建设历程中的“风因素”参与及影响，并在最近四年时间内开展“选点分布均匀、长短路线交织、关键季节突出”的实地风速与风向监测，记录了城市主要开敞空间日常风环境的一手数据；同时利用公开历史气象资料及向专业气象部门咨询，对调研结果加以补充与修正，形成了较为客观的原始数据。在此基础上，重点从城市形态、绿地布局、地形高差、道路衔接、建筑阻碍等方面分析、研判了当前城市通风不利、风道不畅的原因；并依托各类人工与自然空间现状特征，找寻了城市外围“风源”分布、确定了城区边缘“风口”方位、梳理了城区内外“风道”类型及线路，共同构建起理想的西安城市风道分级体系，也提出了总体与分区层面的风道建设标准及规划管控措施。此后，为了进一步落实风道建设的可操作性，提出了“风道+景区”“风道-绿地协同”的规划思路。具体以气候问题较为凸显而通风需求较大的夏季（高温热岛）、冬季（静冷雾霾）作为重点时段，在都市区尺度下对各季中相邻月份地表温度、冷热岛分布进行提取与叠加，得到地表热辐射变化差异，反映出当季地面空气流动的幅度与分布位置；进而结合城乡下垫面建设类型与强度所反映出的通风阻碍情况，得到城市综合通风潜力的等级与分布；之后将现状绿地格局叠加进来，并结合两季较高频风向及上风方位，总结、划分出结合风道体系的“通风特征分区”；最后针对各分区内绿地所处的不同通风潜力、风口主次、风道等级等风环境条件，提出相应的绿地协同通风优化的规划策略；最终选取城市东南部马腾空地区、西南部高新区等几处关键通风分区（如风口与风道衔接地带），尝试绿地、景区与风道、街道的概念规划设计，使在保障通风顺畅的同时，也能达到日常游憩与风环境感知的和谐效果。