摘要
【目的】林道网络及其宽度是林业生产、交通和旅游的需求,在发挥其最大经济效益的同时,兼顾林火巡护监测、应急救援,以及发生火灾时快速运送扑救人员和装备,阻隔森林火灾蔓延和发挥防火隔离功能。【方法】运用火灾动态仿真模拟软件PyroSim分别以坡度25°、35°、45°,风速1、2.5、4.5 m/s,林道宽度2、4.5、6 m构建云南松林微观山体模型,施加长12 m、宽1 m、热释放速率4.6×10^4 kW/m^2的带状火源,模拟中等强度林火研究不同林道宽度的防火阻隔功能。【结果】林道宽度2 m无法满足防火隔离需求。林道宽度4.5 m的防火阻隔功能一般,当坡度超过35°、风速大于4.5 m/s时易失效。林道宽度6 m拥有较强的防火隔离功能,能较好阻隔中等强度的林火蔓延,可满足坡度小于45°、风速小于4.5 m/s的情况,当风速大于4.5 m/s时该林道宽度的隔离功能可能失效。中等强度的森林火灾火场中心温度在700~1200℃左右,热释放功率可达3.0×10^5~9.0×10^5 kW,蔓延山坡10m只需约1 min,可燃物燃烧速率60 s可达到40 kg/s以上。【结论】云南省云南松林区道路宽度建议设置为6 m,能够取得较好的防火效益。常年处于高风速,坡度大于45°,树种高大的林区建议增加林道宽度至8~10 m。此外本研究应用PyroSim建立火场模型仿真模拟林道阻火功能是可行的,可为林区道路建设的合理设计、确定林道密度和宽度的阻火功能指标与经济效益相适应的最大限度阈值、降低森林火灾破坏力具有一定的指导意义。
[Objective]Forest road network and its width is the basic demands of forestry production,transportation,and tourism.While giving maximum economic benefits,its function on forest fire patrol monitoring,emergency rescue,rapid transport of firefighters and equipment when happening fires also should be taken into account,as well as the function of block forest fire spreading and forest fire isolation.[Method]The micro-mountains model of Pinus yunnanensis was constructed using fire dynamic simulation software PyroSim with parameters including slopes of 25°,35°and 45°,wind speed of 1,2.5 and 4.5 m/s,and forest-road widths of 2,4.5 and 6 m.And with the application of belt fire source with 12 m in length and6 m in width,and heat release rate of 4.6×10^4 kW/m^2,which simulated moderate-intensity forest-fire,we aimed to study fire-isolating functions at different forest-road widths.[Result]The forest road width of 2 m failed to meet the need for fire protection and isolation.And the one with 4.5 m achieved relatively poor fireisolating function performance.And the one with more than 35°slope and greater than 4.5 m/s wind speed was easy to lose its function.And 6 m width road got a strong fire isolation function.Comparing with the one that can better isolate medium-intensity forest-fire spreading condition can meet the one with less than4.5 m/s wind speed and less than 45°slope.When wind speed reached more than 4.5 m/s,the fireproof blockade functions of forest-road width of 6 m may be lost.Generally,the central temperature of moderateintensity forest fire was about 700-1200℃.And corresponding heat release rate power can reach 3.0×10^5-9.0×10^5 kW.And it only took about 1 min to spread 10 m on the hill.And the burning rate of combustibles can reach above 40 kg/s in the 60 s.[Conclusion]It is suggested to build the road with 6 m width in P.yunnanensis district in Yunnan Province of southwestern China,which can achieve better fire-prevention benefits.And road with width of 8-10 m is highly recommended in the forest area,where the stands with higher tree height all year round suffering high wind speed and slope greater than 45°.It also approve that the feasibility of simulating forest-road fire-isolating function by constructing the fire-site model with PyroSim,the results in this study have certain guiding significance on the rational designs of forest-road constructions,such as the determinations of maximum threshold values of fire prevention functions of forest-road with indexes of densities and widths,so can achieve certain economic benefits,as well as reductions of destructive powers of forest fires.
作者
高仲亮
李智
魏建珩
龙腾腾
王秋华
舒立福
Gao Zhongliang;Li Zhi;Wei Jianheng;Long Tengteng;Wang Qiuhua;Shu Lifu(Civil Engineering College,Southwest Forestry University,Kunming 650224,Yunnan,China;Institute of Forest Ecological Environment and Protection,Chinese Academy of Forestry,Beijing 100091,China)
出处
《北京林业大学学报》
CAS
CSCD
北大核心
2020年第9期51-60,共10页
Journal of Beijing Forestry University
基金
国家自然科学基金项目(31860214、301660210、31960318)
国家重点研发计划项目(2017YFD0600106)
西南林业大学科研启动基金项目(111437)。
