MICROSCOPIC VISUALIZATION OF ROCKS BY MICRO X-RAY CT UNDER CONFINING AND PORE WATER PRESSURES
利用显微X光CT对围压和孔隙水压条件下岩石试样的细微成像及其分析

To visualize in detail the manner of deformation in rocks under various confining and pore water pressures,a micro X-ray CT system is used to obtain three-dimensional images with a high resolution of 5 (m. A new pressure vessel is developed to simultaneously supply both confining pressure and pore water pressure to rock specimens. Berea sandstone and Noto diatomaceous mudstone specimens with diameter of 10 mm and length of 20 mm are deformed hydrostatically. The diameters at every 15° are measured under various conditions of confining and pore water pressures. The average diameter decreases monotonically with increasing effective confining pressure,which is defined as the difference between confining pressure and pore water pressure. Sensitive orientation around the specimen diameter during pressurization is recognized,deformation anisotropy during pressurization then emerges and the anisotropic ratios reach a maximum value of 8% in the case of Noto diatomaceous mudstone. The method of micro X-ray CT is applicable for deformation measurements of small and irregular rock specimens under various confining and pore water pressures.