Multi-Crack Characterization

在研究期间(1993-1995)，每个研究者的研究成果总结如下：(1)我们通过数值模拟研究了裂缝的普遍性质。结果表明，无论是平面裂纹扩展模型还是三维冲击断裂模型(Takayasu)都具有很强的宏观普适性。(2)建立了考虑地表热释放、地下温度、电阻率结构、居里点深度和富马酸气体惰性气体组成(Yusa)的地热结构综合模型。(3)基于声发射的分维性质，研究了岩石的多重破裂行为。结果表明，用数值模型结合声发射的结果(Hashida)可以分析岩石的多重破裂行为。(4)两种…的无量纲断裂参数表征了裂纹的扩展条件和不稳定振荡提出了一种利用地震波检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，研究了注气对裂缝的影响。提出了一种地震反射资料的AVO反演方法和深度转换技术。研究了增加辅助震源的电流会聚电阻率测井方法(SASA)。(6)提出了一种量化岩体裂隙分布的分形模型，并提出了一种利用地球卫星云图的线形分析来确定模型输入参数的方法。将所提出的方法应用于一个花岗岩田，估计了裂隙的分布和裂隙的连通性(金子)。(7)将航空照片和卫星图像的分析数据与地质识别的天然裂隙系统进行了对比。通过伽马射线测量追踪了地质上未定义的线形构造。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、大小(位移)分布以及断层和断层位移的空间分布呈分维分布，其分维随岩石延性和注入总能量密度(Ohtsuki)而变化。(9)地壳弹性波速和密度的结构是不均匀的。分析了日本九州和关东5口井的测井资料，发现它们的功率谱在几十厘米到几百米(佐藤)的宽波长范围内服从幂定律。(10)用分割法测量的焊接凝灰岩试件劈裂断口的分维与强度几乎成反比。另一方面，CT试件中预裂纹处的尺寸变异系数与断裂韧性(TANO)成正比。较少

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