Multi-Crack Characterization

研究期间（1993-1995年）取得的成果总结如下：(1)通过数值模拟研究了断裂的普遍特性。证明了平面裂纹扩展模型和三维冲击断裂模型（Takayasu）具有很强的宏观通用性。(2)建立了考虑地表放热、地下温度、电阻率结构、居里点深度和富马酸气体（Yusa）惰性气体组成的地热构造综合模型。(3)基于声发射的分形特性，研究了岩石的多重裂纹行为。结果表明，结合声发射结果的数值模型可以分析岩石的多重裂纹行为（Hashida）。(4)裂纹扩展和不稳定振荡的条件均采用无因次断裂参数来表征（Sano）。(5)提出了一种利用地震波探测和监测裂缝的新方法。采用模型实验和数值模拟相结合的方法研究了裂隙内注入空气的效果。提出了地震反射资料AVO反演方法和深度变换技术。研究了增加辅助源的电流收敛电阻率测井（Sasa）。(6)提出了一种量化岩体裂纹分布的分形模型，并提出了一种利用地球卫星图像的纹理分析来评价模型输入参数的方法。将该方法应用于花岗岩现场，对裂缝的分布和连通性进行了估计（kaneko）。(7)将航空照片和卫星图像分析数据与地质识别的天然裂缝系统进行了对比。地质上未确定的轮廓是用伽马射线测量描画出来的。介绍了一种新的卫星图像分析方法（Takashima）。(8)对6组1500条断层的分形分析表明，剪切带宽度与断层位移、断层大小（位移）分布、断层与断层位移的空间分布呈分形分布，分形维数随岩石延性和注入总能量密度的变化而变化（Ohtsuki）。(9)地壳的弹性波速和密度结构是不均匀的。分析了日本九州和关东地区5口井的测井数据，发现其功率谱在几十厘米到几百米的波长范围内服从幂律（Sato）。（10）分频法对焊接凝灰岩试样劈裂断口的分形维数与强度几乎成反比。另一方面，CT试样中预裂纹附近的尺寸变异系数与断裂韧性（Tano）几乎成正比。少

Results obtained during the research term (1993-1995) are summarized for each researcher in the following :(1) We investigated universal properties of fracture by numerical simulations. It was proven that strong macroscopic universality holds both in the cases of crack propagation model on a plane and of 3-dimensional impact fracture (Takayasu).(2) Asynthetic modelling of geothermal structure was developed which accounts for the heat discharge at the surface, the subsurface temperature, the electric resistivity structure, the Curie point depth and the inert gas composition of fumarolic gas (Yusa).(3) The multiple cracking behavior in rock was examined based on the fractal nature of acoustic emission (AE). It is demonstrated that the multiple cracking behavior in rock could be analyzed using a numerical model in conjunction with the AE results (Hashida).(4) The conditions for propagation and unstable oscillation of cracks were characterized by nondimentional fracture parameters for both … More single crack and multiple cracks (Sano).(5) A new method of detecting and monitoring fractures by use of seismic waves was proposed. The effect of injecting air into fracture was nvestigated by using both model experiments and numerical simulations. An AVO inversion method and a depth transform technique of seismic reflection data were developed. A current-convergent resistivity log by adding auxiliary sources was investigated (Sasa).(6) A fractal model to quantify the crack distribution in rock masses and a method to evaluate model input parameters by a lineament analysis of earth satellite image have been proposed. By applying the proposed method to a granite field, the crack distribution and the connectivity of cracks have been estimated (kaneko).(7) Analytical data of aero-photo and satellite images were compared with geologically identified natural fracture systems. Geologically undefined lineaments were traced by gamma ray survey. A new analytical method for satellite image was introduced (Takashima).(8) The fractal analysis on the 1500 faults of 6 groups suggests that the relationship between the width of shear zone and fault displacement, size (displacement) distribution, and the spatial distributions of faults and fault displacements show the fractal distributions whose fractal dimensions change depending on the ductility of rocks and the total energy density injected (Ohtsuki).(9) The structure of elastic wave velocity and density of the crust is known to be heterogeneous. Analyzing the well-log data obtained at 5 wells in Kyushu and Kanto, Japan, we found that their power spectra obey a power law for a wide range in wavelength from a few tens of centimeters to a few hundred meters (Sato).(10) Fractal dimensions of splitting fracture surface of welded tuff specimens using by divider method are nearly in inverse proportion to the strength. On the other hand, the coefficient of variation of dimensions near the pre-crack in CT specimens are nealry in proportion to the fracture toughness (Tano). Less