红松针叶床层风影响因子的模拟

A Simulation on Wind Factors of Fuelbed of Korean Pine Needles

以红松人工林的针叶为材料,在实验室内根据过去平地无风研究的试验设计,构建不同载量、高度和含水率的可燃物床层;在各层级风速条件下,共进行87次平地点烧试验。结果表明:风速在0.9～4.6 m·s-1时,红松针叶床层的风因子为1.24～14.51。现有风因子模型对红松均不适用,模型形式与参数合理化后,幂函数形式模型好于指数函数形式模型,含床层因子的多因子模型好于单因子模型。床层因子中,床层压缩比、含水率对风因子影响显著,二者的误差降低比例分别为3.7%～8.2%和2.9%～5.4%。床层载量与床层厚度对红松针叶床层风因子影响不大。以风速和可燃物床层压缩比为预测因子的多因子形式模型能够解释45.3%的风因子变差,模型的平均绝对误差为1.727,平均相对误差不超过28%;但分别以压缩比和含水率建立的新的风因子模型,则进一步提高了模型的精度,平均绝对误差降到1.03,平均可解释75.6%的风因子变差。

According to an experimental design in our previous study,fuelbeds were constructed with varied fuel moisture,loading and depth of Korean pine （Pinus koraiensis） needles collected from Korean pine plantations.Totally 87 experimental fires with these fuelbeds were burned in laboratory under different wind conditions.The results showed that wind factor was in 1.24-14.51 when wind speed was in 0.9-4.6 m· s-1 The existing models of wind factor are not applicable for Korean pine needles.The model parameter rationalization displayed that the power function model was better than the exponential function model and the multi-sector model was better than the single factor model.Packing ratio and fuel moisture significantly influenced wind factor and their relative error reduction ratio was from 3.7% to 8.2% and 2.9% to 5.4%,Respectively.The effect of fuel loading and fuelbed depth on wind factor was not significant.The wind factor model established with wind speed and packing ratio as predictive variables can account for 45.3% variance of wind factor with mean absolute error of 1.727 and mean relative error less than 28%.Model accuracies were significantly improved when established by packing ratio and fuel moisture with MAE of 1.03 and 75.6% of variance of wind factor explained.