裂隙砂岩破坏过程中的能量耗散与破碎分形特征研究

对不同裂隙倾角的裂隙砂岩试件进行单轴压缩试验，分析了试件变形破裂过程中的应变能演化特征，基于分形理论定量描述了最终破坏后碎屑尺度分布的分形特征，初步探究了能量耗散与破碎分形维数之间的力学机制。研究结果表明：随着裂隙倾角增加，裂隙砂岩试件的抗压强度和耗散应变能均呈现出先减小后增大的变化规律；数据拟合结果表明两者之间存在正相关关系。试件破坏后的碎屑尺度分布具有分形特征，不同裂隙倾角试件的分形维数介于2.58～2.64;分形维数随裂隙倾角的变化规律与抗压强度类似，两者近似呈线性相关关系。此外，试件的抗压强度越高，破坏时释放的耗散应变能越多，试件破碎程度越严重，所产生的微、细粒碎屑占比增大，导致分形维数变大；数据拟合结果表明耗散应变能和分形维数之间具有线性正相关关系。

Investigation on correlation between energy dissipation and fractal characteristics of fragments of preflawed sandstone

This paper aims to investigate the correlation between the energy dissipation and fractal characteristics of fragments of preflawed sandstone. First, the uniaxial compression tests on preflawed sandstone with different flaw inclinations were conducted to analyze the energy evolution characteristics of preflawed sandstone during loading. Based on fractal theory, the size distribution characteristics of fragments after final failure were quantitatively characterized. The study shows that the compressive strength and the dissipation strain energy of specimen first decrease and then increase with the increase of flaw inclination and the data fitting suggests a positive correlation between them. The fragment size distribution of fragments under the uniaxial compression tests has obvious fractal property. The fractal dimensions of specimens with different flaw inclinations are in the range of 2.58-2.64. The trend of fractal dimension changing with flaw inclination is similar to that of compressive strength, and fractal dimension and compressive strength are approximately linearly related. The higher the compressive strength of the specimen is, the more the dissipative strain energy releases during failure. At this time, the more severe failure the specimen has, the greater the proportion of micro and fine particles is, resulting in the increase of fractal dimension. The regression analysis shows the relationship between dissipation strain energy and fractal dimension is linear positive correlation.