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为得到岩石试样在各种围压和孔隙水压条件下的成像并分析其变形,利用显微X光CT系统获得具有5μm高分辨率的三维图像。为此,设计和制造了一个可以对岩石试样同时加围压和孔隙水压的新型压力容器。用此容器,对高20mm、直径10mm的Berea砂岩及Noto硅藻泥岩试样施加静水压并使之变形。在各种围压和孔隙水压条件下,每隔15°测试其径向尺寸。试样的平均直径随着有效围压的增长而单调减小。在此,有效围压被定义为围压和孔隙水压之差。随着有效围压的增加,其直径的变化根据不同的方向而不同,即其变形的各向异性特征得到了证实。Noto硅藻泥岩试样的各向异性比最大,达8%。实验结果表明,此显微X光CT方法可用来测试在各种围压和孔隙水压条件下一般方法很难测得、小或不规整试样的变形。
To obtain images of rock samples under various confining pressure and pore pressure conditions and analyze their deformation, a three-dimensional image with a high resolution of 5 μm was obtained using a micro X-ray CT system. To this end, a new type of pressure vessel designed and manufactured to simultaneously compressive and pore water pressure on rock samples was designed and manufactured. Using this container, hydrostatic pressure was applied and deformed to Berea sandstone and Noto diatomaceous mudstone samples 20 mm in height and 10 mm in diameter. The radial dimensions were tested at 15 ° intervals for various confining pressures and pore pressures. The average diameter of the sample monotonically decreases with the increase of effective confining pressure. Here, the effective confining pressure is defined as the difference between confining pressure and pore water pressure. With the increase of effective confining pressure, the change of diameter varies with different directions, that is, the anisotropy of deformation has been confirmed. The anisotropy ratio of Noto diatomite samples is the largest, up to 8%. The experimental results show that this X-ray micro-CT method can be used to test the deformation of the sample which is hard to measure, small or irregular under various confining pressure and pore pressure conditions.