基于模拟点烧不同加热时间和腐殖质粒径对森林地下火垂直燃烧的影响

  目的  森林地下火是一种缓慢、无焰、持续时间长的阴燃，对森林危害极大。大兴安岭地区是我国森林地下火频发区域，研究不同加热时间和腐殖质粒径对地下火垂直燃烧的影响，旨在为该地区森林地下火的预防、监测、扑救提供参考。  方法  以大兴安岭地区典型林型兴安落叶松林为研究对象，根据室内控制模拟点烧实验数据，使用SPSS进行双因素方差分析，Origin软件绘图，研究3种加热时间和5种腐殖质粒径对地下火垂直燃烧过程中蔓延速度和不同深度最高温度的影响。  结果  森林地下火垂直燃烧过程中，深度3 cm处燃烧最高温度只受加热时间的影响且差异显著（P < 0.05），而腐殖质粒径对其的影响则差异不显著（P > 0.05）；深度6 cm处的燃烧最高温度分别受加热时间（P < 0.05）和腐殖质粒径（P < 0.05）的影响；当深度大于6 cm后燃烧的最高温度则只受腐殖质粒径的影响并且差异显著（P < 0.05）。森林地下火垂直燃烧过程中的蔓延速度则只受腐殖质粒径的影响，不同腐殖质粒径之间的蔓延速度存在显著差异（P < 0.05）。  结论  森林地下火垂直燃烧3和6 cm处的最高温度随着加热时间的增加而升高，加热2 h时的燃烧温度最高；垂直燃烧深度9～21 cm时，腐殖质粒径40目的燃烧温度最高；不同腐殖质粒径对森林地下火垂直燃烧蔓延速度的影响中，腐殖质粒径20目的蔓延速度是最快的；腐殖质粒径60目时，是地下火燃烧过程中的临界，燃烧的最高温度和蔓延速度都较低。 

Effects of different heating times and humus particle sizes on vertical combustion of forest underground fire based on simulated spot burning

Objective]The combustion of underground fire is a slow,flameless,long duration smoldering,which does great harm to forest.Daxing’anling region is a frequent area of forest underground fire in northeastern China.This paper aims to study the effects of different heating times and humus particle sizes on the vertical combustion of underground fires,aiming to provide a reference for the prevention,monitoring and suppression of underground fires in the area.Method]Taking the typical forest type in the Daxing’an Mountains,i.e.Larix gmelinii forest as the research object,according to the indoor control simulation of scorching experiment data,SPSS was used to perform two-factor analysis of variance,and the Origin software was used to draw.The effects of three heating times and five humus particle sizes on the spreading speed and the highest temperature at different depths during the vertical combustion of underground fire were studied.Result]During the vertical burning process of the forest underground fire,the temperature of the highest burning at a depth of 3 cm was only affected by the heating time and the difference was significant(P<0.05),but the effects of humus particle size on the difference were not significant(P>0.05).The highest temperature of combustion at a depth of 6 cm was affected by the heating time(P<0.05)and the particle size of humus(P<0.05).When the depth was greater than 6 cm,the maximum combustion temperature was only affected by the humus particle size and the difference was significant(P<0.05).The spread rate during the vertical combustion of forest underground fires was only affected by the humus particle size.There were significant differences between the spreading speeds(P<0.05).Conclusion]The highest temperature of underground forest fires burning at 3 cm and 6 cm depth rises with the increase of heating time,and the burning temperature is the highest when heated for 2 h.When the vertical combustion depth is 9-21 cm,the humus particle size is 40 mesh,the burning temperature is the highest.Among the effects of humus particle size on the spread speed of forest underground fires,the spread speed of humus particle size 20 mesh is the fastest;when the humus particle size is 60 mesh,it is the criticality in the process of underground fire combustion.The highest combustion temperature and spread speed are lower.