岩石单轴压缩试验的应力应变分形特征研究

Research on the fractal characteristic of the rock's stress and strain under uniaxial compression

为了定量描述岩石力学试验过程中得到的应力应变曲线的不平滑特征,提出一种新的表征岩石破坏过程的分形维计算对象——应力应变分形。应力应变的记录过程连续且受外界干扰相对较少,基于此计算的应力应变分形对于研究岩石的破坏特征具有实际意义。通过对两组花岗斑岩进行单轴压缩试验,得到其应力-时间曲线、应变-时间曲线和应力应变曲线,提取曲线关键位置的图像并计算其分形维。通过分析发现当应力、应变发生突变时,对应的分形值也发生突变,两者具有较好的一致性。

In order to quantitatively describe the unsmooth characteristic of the stress and strain curves obtained in the rock me-chanic experiments,a new calculation object,namely,the fractal dimension of the rock's stress and strain,was provided to de-scribe the process of rock failure.The recording process of the stress and strain was continuous and the external disturbance was relatively small,so that the fractal characteristic of the rock's stress and strain showed practical significance for investigating rock failure.Through the uniaxial compression experiments of the granite porphyry,the stress-time,strain-time,and stress-strain curves were obtained.The images of the key position in the curves were extracted and calculated to obtain the fractal dimension. By analyzing the fractal feature,it was found that the corresponding fractal values changed and showed a good consistency when the stress and strain changed.