Study on groundwater flow and transport properties considering the structural change of fracture system in rock masses.

通常认为，花岗岩中的流体流动主要通过节理、裂隙和裂隙等不连续面来进行。然而，并不是所有的不连续都是管道。流体流动路径是如何形成的？对Stripa矿、Aspo硬岩实验室和Kamaishi矿裂隙系统的研究表明，流体的流动路径主要与裂隙的位移和地应力状态有关。通过排水三轴压缩试验，研究了剪切变形对中新世砂岩Shirahama SS水力性质的影响。Olsen等人提出的流量泵法。(1985)用来测量水力传导性。要渗透的水向两个方向流出，即加载方向和垂直加载方向。这些测试表明，这两个测试的峰值应力下的水力传导率都比最初的增加了大约三倍。为了检测含裂隙系统岩石的变形和水力特性，我们研制了三轴试验机，利用体视显微镜动态观察试件的表面微结构。在本研究中，我们首先给出了一些单轴压缩试验的结果。同时用体视显微镜观察了实验产生的断口的剪切过程。桥梁发生旋转和切割，在断裂面上滑动，裂缝张开。此外，通过薄片观察可以清楚地看出，这些结构在试件内部是连续的。其次，对裂缝性白哈马砂岩进行了三轴压缩渗透性试验。试验表明，沿裂缝滑动主要发生在峰值应力和渗透系数突然增大之后。

It is commonly accepted that fluid flow in granitic rocks mainly occurs through discontinuities such as joints, fractures and cracks. However all of discontinuities are not always the conduits. How do the fluid flow path form? The investigations of fracture system in Stripa mine, Aspo Hard Rock Laboratory and Kamaishi Mine suggest that fluid flow path mainly relates to the displacement along the fractures and in situ stress regime.The effect of shear deformation on hydraulic properties of Miocene sandstone, Shirahama Ss, was investigated in drained triaxial compression experiments. Flow pump method developed by Olsen et al. (1985) is adopted in order to measure the hydraulic conductivity. The water to permeate was run out to two directions, that is the loading direction and the vertical to loading. These tests show that hydraulic conductivities at the peak stress for both tests increase about three times as large as the initial ones. The difference of hydraulic properties due to flow direction is now in consideration.In order to examine the deformational and hydraulic properties of rock with fracture system, we developed the triaxial testing machine, in which the surface microstructure of specimen can be observed in a motion using a stereoscopic microscope. In this present study we first showed some experimental results in uniaxial compression test. The shearing process on fractures experimentally generated is simultaneously observed by stereoscopic microscope. The rotation and cutting of bridge, sliding on fracture plane and opening of fracture occur. Furthermore it is clear that these structures are continued inside the specimen by thin section observation. Next, permeability tests under triaxial compression were conducted for fractured Shirahama sandstone. The tests show that the slide along fractures mainly occur after the peak stress and hydraulic conductivity abruptly increase.