Co-operative Study on a New Rock Fracture Mechanics based on Fractal Geometry

基于分形几何的新型岩石破裂力学合作研究

• 批准号: 04305001
• 负责人: TAKAHASHI Hideaki
• 金额: $ 8.7万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Co-operative Research (A)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04305001/
• 关键词: FRACTURE; FRACTAL; SUBSURFACE FRACTURES; NUMERICAL SIMULATION; ROCK

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 water-saturated at ambient temperature and pressure. The constant stress intensity, K_I, and quantitative analyzes 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 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.

断层长度分布和地震幅度频率分布的观察到的分形性质表明，活动断层系统的结构与所得的地震性之间可能存在关系。在这里，我们提供了第一个实验证据，证明了基于在不同环境条件下在不同环境条件下进行的一系列拉伸裂缝力学测试，基于一系列抗晶体岩石的拉伸断裂力学测试，裂缝长度分布D的分形尺寸与声发射（AE）B值（AE）B值，这两者都在环境温度和压力下进行空气干燥的水。在相同的标本上对所得断裂模式的恒定应力强度，K_I和定量分析进行了定量分析。发现AE B值范围为1.0至2.3，与归一化的应力强度K_I/K_ <ic>负相关，其中K_ <ic>是样品的断裂韧性。断裂长度分布D的分形维度为1.0至1.7。流体的存在对这些实验中产生的AE和结构都有一阶影响。对于低应力或高流体含量下的实验，K_I <k_ <ic>的应力腐蚀机制的激活导致相对比例较大，而小裂纹和低振幅声学发射都反映在较高的d和b值中。发现分形维度D与AE B值正相关。

项目成果

C.G.Hatton,I.G.Main and P.G.Meredith: "A Comparison of Seismic and Structural Measurements of Scaling Exponents during Tensile Subcritical Crack Growth" Journal of Structural Geology. 15. 1485-1495 (1993)

C.G.Hatton、I.G.Main 和 P.G.Meredith：“拉伸亚临界裂纹扩展期间尺度指数的地震和结构测量的比较”结构地质学杂志。

I.G.Main, P.R.Sammonds and P.G.Meredith: "Application of a Modified Griffith Criterion to the Evolution of Fractal Damage during Compressional Rock Failure" Geophys.J.Int.Vol.115. 367-380 (1993)

I.G.Main、P.R.Sammonds 和 P.G.Meredith：“修正格里菲斯准则在压缩岩石破坏过程中分形损伤演化中的应用”Geophys.J.Int.Vol.115。

K.Watanabe and H.Takahashi: "A Model Analysis of Long-term performance of Hot Dry Rock Geothermal Energy Extraction System" Proceeding of the JSME-ASME International Conference on Power Engineering '93. 1. 453-458 (1993)

K.Watanabe 和 H.Takahashi：“干热岩地热能提取系统长期性能的模型分析”，JSME-ASME 国际电力工程会议 93 论文集。

K.Watanabe and H.Takahashi: "Fractal Choracterization of Subsurface Fracture Network for Geothermal Energy Extra" Proc. of 18th Workshop on Geothermal Reserver Eng., Stanford. (1993)

K.Watanabe 和 H.Takahashi：“地热能额外的地下裂缝网络的分形分类”Proc。

K.Watanabe and H.Takahashi: "Parametric Study of the Energy Extraction from Hot Dry Rock Based on Fractal Fracture Network Model" Geothermics. (未定). (1994)

K.Watanabe 和 H.Takahashi：“基于分形断裂网络模型的干热岩石能量提取的参数研究”地热学（TBD）。