Preliminary Study on the Characteristic of Rock Microscopic Damage Based on the Technique of CT Image Processing under the Frost and Thaw Condition
|School||Xi'an University of Science and Technology|
|Keywords||frozen rock damage characteristic of propagation CT image digital image processing Digital Image Processing—Finite Element Method|
The technology of CT provides us with more efficient means for studying on the characteristic of rock microscopic damage propagation, however, the existing CT analysis methods haven’t made the best use of CT image which are supplied by the experimental outcome. This thesis puts forward a new method, Digital Image Processing—Finite Element Method. The proposed method incorporates the principle of digital image processing and geometry vectorization algorithms into the conventional finite element methods.By this means the author not only researches the characteristic of rock microscopic damage propagation based on the theory of damage mechanics but also makes a preliminary analysis for the influence of inhomogeneity of initial damage on the damage propagation under the negative temperature condition.The author studies on the technology of image reinforcement, image segmentation and edge test about CT image of shale rock, and then obtains the realistic micro-structure image in the rock. According to the histogram of CT image we quantificationally and dynamically analyze the damage propagation of rock under different damage stages. A new damage variable is brought up which takes the number of pixel to be as reference quantity. The binary micro-structure image was changed into vectoranation micro-structure image, then it was read into finite element software ANSYS. Lastly, the author simulates the distribution law of transient temperature field of frozen rock that has different ratioes of pore and moisture content.The studying results show that: the worse the initial damage, the higher the ratio of pore and moisture content; the shorter the frozen (melted) cycle. The damage speed of rock will be quickened under the action of long-term frost and thaw cycle.The morphology of temperature distribution firstly occurs at the place where there are small fissure and pore.