不同岩性风化物分形特征及其与渗透系数关系研究

为了探讨不同岩性风化物的结构组成和渗透性能，在野外采样和室内分析的基础上，选择小江流域9种岩性风化物作为研究对象，采用分形理论，分析了不同岩性风化物的分形特征及其与渗透系数之间的关系。结果表明:（1）岩性风化物具有显著的分形特征，分形维数值为2.567～2.833，其关系为白云岩 > 砂岩 > 第四纪沉积 > 玄武岩 > 千枚岩 > 泥质灰岩 > 粉砂岩 > 板岩 > 泥岩；（2）分形维数与 < 0.005，0.005～0.05 mm的粒径含量呈极显著正相关，与10～20，20～40，40～60 mm的粒径含量呈极显著负相关，与其他粒径含量相关性不显著；（3）多元线性回归分析发现， < 0.05 mm的粒径是决定不同岩性风化物分形维数的决定粒径；（4）分形维数与渗透系数呈显著的一次函数关系:y=-276.84x+810.66，分形维数越大，细颗粒物质越多，渗透系数越小，渗透能力越差。因此，分形维数可以作为表征不同岩性风化物粒级组成和渗透性能的参数，可以为泥石流起动发生的研究提供一定的理论依据。

Study on Fractal Feature and Relationship Between Fractal Dimension and Permeability Coefficient of Weathered Materials of Different Lithologies

Based on the field sampling and laboratory analysis,the fractal feature and relationship between fractal dimension and permeability coefficient of 9 types of weathered materials of lithology were studied by using the fractal theory.The results showed that different weathered materials of lithology had significant fractal characteristics,the dimension values were between 2.567 to 2.833,and the order followed the sequence:dolomite＞sandstone＞quaternary sedimentary＞basalt＞phyllite＞limestone＞powder sandstone＞ slate＞mudstone.With the fractal dimension values for the dependent variable,the content of particle size for the independent variable,the equation was built up,the results showed that the fractal dimension had a significant linear positive correlation to the content of ＜0.005 mm particle size and 0.005～0.05 mm particle sizes,and a significant negative correlation to the contents of 10～20 mm,20～40 mm and 40～60 rm particle sizes.There was no significant correlation with other particles.Furthermore,by the multiple linear regres sion analysis,the fractal dimensions of different weathered materials of lithology were contolled by ＜0.05 mm size particle.A linear equation between fractal dimension and permeability coefficient was fitted by regression analysis,the function was expressed as y=-276.84x+810.66 with 0.919 of R2 value,it was suggested that there was a good correlation between fractal dimension and permeability coefficient.In the other word,this showed that the bigger the fractal dimension,the more fine particulate matter,the smaller the coefficient of permeability,and the worse the infiltration capacity.As a result,the fractal dimension can be used as the parameter to characterize the graded composition and permeability of different weathered materials of lithology,and it can provide certain theoretical basis for the research on debris flow starting.