风化岩石的破碎分形及其工程地质意义

利用分形统计的方法,对风化花岗岩矿物成分的粒度分布特征进行了分析和统计,并根据分析的结果指出,岩石的风化破碎过程具有分形特征。其粒度分布的双对数曲线为多段折线,不同斜率的折线段对应不同的分形维。因此,分形维至少有2个数值,一为结晶颗粒粒度分形维,一为碎裂颗粒粒度分形维。同时,根据试验结果和理论分析得到,碎裂粒子的累积频率分布也符合指数分布,并给出了用指数分布系数求解碎块的碎裂概率的理论计算公式。随后,讨论了碎裂分形维和岩石强度与颗粒结构的关系,并以岩石的降维碎裂演化,得到以分形维描述的岩石风化速率。

FRACTAL FRAGMENTATION OF WEATHERED ROCK AND ITS APPLICATION IN ENGINEERING GEOLOGY

Statistical analysis on size distribution of mineral particle of weathered granite is carried out by using fractal method. The results show that the fracture process of weathering is a fractal one. The double logarithmic curves of particle number and particle size are folded lines,and each linear section in the curve corresponds to different fractal dimension. There are at least two fractal dimensions of the particle size distribution of weathered rock,one is the fractal dimension of crystallized mineral particles and the other is the fractal dimension of fractured particles. Based on the test result and theoretical analysis,it is pointed out that the accumulative frequency of particle size distribution has feature of exponential law. The formula for calculating the friable possibility of rock blocks by using exponential coefficient is also presented. Subsequently,the relationship among the shear strength,microstructure and fractal dimension is discussed. Based on the dimension reduction evolution of rock fracturing,the rate of weathering in term of fractal dimension is obtained.