泥石流源区砾石土的粒度分形特征

Particle Size Fractal Characteristics of the Gravel Soil in Original Area of Debris Flow Valleys

以19条泥石流沟源区75个砾石土试样的颗分数据为基础,应用分形理论研究泥石流沟源区砾石土粒度组成特征,并对粒度分形特征与土体颗粒组成的关系进行了讨论。结果表明:1.粒度分布具有分形特征,以一重分形特征为主;2.一重分形特征表明土体各粒组的含量连续分布性较好;二重分形表明土体各粒组的含量连续分布相对较差,某一粒组含量存在突变;3.所研究的沟道平均粒度分维值Da在2.45～2.78间,且平均粒度分维值Da随粘粒含量Pc增加逐渐增大,具有一重分形特征的沟道二者满足关系式Da=0.108ln(Pc)+2.511。最后探讨了研究源区砾石土粒度分形特征的意义。

Based on the particle distribution of 75 gravel soil samples from 19 debris flow valleys ,the fractal theory is applied to study the characteristics of particle composition of gravel soil , the relationship between the characteris- tics of fractal dimension and particle composition is discussed later. The results show that：l, the gravel soil posses- ses the characteristic of fractal, and mainly in one dimension fractal ;2. particles with one dimension fractal is fine graded ; particles with two dimension fractal is weak graded, and it emerges when there exists a particle abrupt ;3. the average particle size fractal is between 2.45 and 2.78 in the 19 debris flow valleys, and it goes up with the increas- ing of clay content. The relationship between particle size fractal in one dimension and clay content can be ex- pressed by： Da = 0. 1081n （pc） ＋ 2. 511. At last, the significance of researching on the fractal characteristics of gravel soil in original area of debris flow valleys is discussed.