Characterization of the Subsurface Fracture Network by Means of Crystal Fracture Mechanics and Crystal Stress Study

所观察到的分形性质的断层长度分布和地震震级-频率分布表明，有可能是一种关系的结构之间的活动断层系统和由此产生的地震活动。在这里，我们提出了第一个实验证据之间的相关性的分形维数的裂缝长度分布D和声发射（AE）b值的基础上一系列的拉伸断裂力学测试结晶岩石，在不同的环境条件下进行，空气干燥和水饱和在环境温度和压力。在相同的试样上进行了恒定应力强度K_I和由此产生的断裂模式的定量分析。结果表明，AE b值（1.0 ~ 2.3）与归一化应力强度因子KI/K_1<IC>（K_1<IC>是试样的断裂韧性）呈负相关。裂缝长度分布的分形维数D的范围为1.0至1.7。流体的存在有一个一阶的影响，在这些实验中产生的AE和结构。对于低应力强度或高流体含量的实验，K_I &lt; K_I的应力腐蚀机制的激活导致<IC>小裂纹和低振幅声发射的相对比例更大，反映在更高的D和B值上。分形维数D与AE b值呈正相关。

The observed fractal nature of both fault length distributions and earthquake magnitude-frequency distribution suggests that there may be a relationship between the structure of active fault systems and the resulting seismicity. Here, we present the first experimental evidence for a correlation between the fractal dimension of fracture length distribution D and acoustic emission (AE) b-value based on a series of tensile fracture mechanics tests on crystalline rock, carried out in different environmental conditions, both air-dry and water-saturated at ambient temperature and pressure. The constant stress intensity, K_I, and quantitative analyses of the resulting fracture patterns were carried out on the same specimens. It is found that AE b-values, ranging from 1.0 to 2.3, correlate negatively with normalized stress intensity K_I/K_<IC>, where K_<IC> is the fracture toughness of the specimen. The fractal dimension of fracture length distribution D, ranges from 1.0 to 1.7. Fluid presence has a first-order influence on both the AE and structure produced in these experiments. For experiments at low stress intensity or high fluid content, the activation of the stress corrosion mechanism for K_I < K_<IC> leads to a greater relative proportion both of small cracks and of low amplitude acoustic emissions, reflected in higher values of D and b. The fractal dimension D is found to correlate positively with the AE b-value.