森林雷击火发生规律研究

Study on the occurrence law of forest lightning fire

雷击是森林火灾的重要点火源。文章研究了雷击的位置与地表可燃物的关系,采用冲击电压发生器测量了三种典型针叶床的击穿电压值。结果表明:新疆云杉针燃料床和西伯利亚松针燃料床的击穿电压值差别不大,马尾松针燃料床击穿电压最低。另外,研究了不同含灰率对泥土电阻率的影响,结果表明:含灰率越大,电阻率越低,经过人工烧除后的迹地更容易遭受雷击。采用冲击电流发生器来模拟雷击过程,并结合Taylor的假设探究了森林雷击火的形成过程。最后,比较了典型植被结构中树木和草的雷击临界着火特性,发现草比木片更容易被雷电引燃。

Lightning strike is an important ignition source of forest fires.As the global warming,forest lightning fire is becoming more and more serious.In this paper,the relationship between the position of lightning strike and ground combustible matter was studied,and the breakdown voltages of three typical conifer beds were measured by the impulse voltage generator.The results show that there is little difference in the breakdown voltage between Xinjiang spruce needle bed and Siberian pine needle bed.The breakdown voltage of Pinus massoniana Lamb.needle bed is the smallest.In addition,the effect of ash content on the resistance of soil was studied.The results show that the higher the ash content is,the lower the resistance is.The site after prescribed burning is more vulnerable to lightning strike.The impulse current generator was used to simulate the lightning strike process,and it is found that the combustible matter can be ignited and produce mars splashing under the action of impulse current.Combined with the hypothesis of Taylor,the formation process of forest lightning fire was discussed.Finally,the lightning critical ignition characteristics of typical vegetation structure(tree and grass)were compared,and it is found that the grass is more likely to be ignited by lightning than the wood chip.