长白落叶松人工林采伐迹地土壤火灾温度场试验研究

Experimental study on soil fire temperature field of harvested site of Larix olgensis plantation

建立长白落叶松人工林采伐迹地燃烧床试验模型,进行火灾模拟试验,利用热电偶测温系统得出火灾过程中500、1000、1500 s时各层土壤测试点的温度数据,将数据以图像的形式展现,得出火灾过程中各层土壤温度场的变化情况.结果表明:当风速≤2 m·s^(-1)或≥10 m·s^(-1)时,可燃物均无法充分燃烧;在可燃物充分燃烧的情况下,风速为6 m·s^(-1)时,各层土壤温度最高,土层受高温影响深度在12 cm以上,其中3 cm层土壤最高温度可达300℃.与非伐根处土壤相比,伐根处土壤在火灾过程中最高温度更大,且距离伐根越近的位置土壤温度越高.风速为6 m·s^(-1)时,3 cm层土壤距离伐根最远处到最近处的温度范围为198～315℃.随着土壤深度的加深,土壤温度的变化急剧减小.15 cm层土壤温度几乎无变化;12 cm层土壤仅在风速为6 m·s^(-1)时温度有所升高;3 cm层土壤温度最高.当风速为6 m·s^(-1)时,土壤温度受火灾影响最大,且伐根处土壤受损最严重.

We established a fire simulation experiment in the harvested site of Larix olgensis plantation and recorded the temperature of each test point at 500, 1000 and 1500 s during the fire by thermocouple temperature measurement. The data were displayed in the form of images to show soil temperature field at each layer during the fire. The results showed that when the wind speed was less than or equal to 2 m·s^-1 or greater than or equal to 10 m·s^-1, combustibles could not be fully burned. In the case of full combustion of combustibles, soil temperature at each layer was the highe-st when the wind speed was 6 m·s^-1, with the affected soil depth being up to 12 cm or more. The maximum temperature at soil layer of 3 cm could reach 300 ℃. Compared with that at the non-cut stump, soil at the stump had a higher maximum temperature during the fire, with the soil temperature being higher near the stump. When the wind speed was 6 m·s^-1, the temperature range at soil layer of 3 cm from the farthest and the nearest to the stump was from 198 ℃ to 315 ℃. With the deepening of soil layer, soil temperature sharply decreased. The temperature at the soil layer of 15 cm was almost unchanged during the fire test. The temperature at the soil layer of 12 cm was increased only when the wind speed was 6 m·s^-1, and the temperature at the soil layer of 3 cm was the highest. When the wind speed was 6 m·s^-1, the influence of fire on the soil temperature was the greatest, and soil at stump had the severest damage.