Study On The Breakage Meso-mechanism Of The Sandstone Through The Image Quantitative Analysis

Firstly, the experimental theory of the rock and soil mechanics computed tomography (abbreviation, CT) is simply presented. Simultaneously, the current CT research about the mechanics behaviors of the rock and soil material is also summarized and analyzed. The deficiency of the current research used and the trend are discussed, too. Moreover, a set of measuring and description method that contains geometric information such as the length, width, area and figure factor of crack and physical data (for example the CT number) is developed to quantitatively analyze the CT data on the basis of the introduction of the mathematic morphology, set theory, matrix theory, measure theory and computer image science. Finally, by means of the pick-up arithmetic and the determinant law of crack the binary images of crack are picked up under the condition of the threshold of CT number C which equals 20, and taking them images of crack as example illustrate the quantitative description. Then the aim of the geotechnical CT image described quantitatively comes into true. Simultaneously, the definition, quantitative description and evolution of ROI(region of interest, abbrev. ROI) are realized, too.Based on the idea of partition description used in image disposal, the CT data ofcertain sandstone divided into parts is described. After the minimum and maximum of CT number on the whole region defined are traced, the experienced thresholds of the CT number for subarea are confirmed, ζ ₁ equals 50, ζ₂ equals 100, based on these the ROS(region of safety, abbrev. ROS), ROD(region of damaging, abbrev. ROD) and ROB(region of breakage, abbrev. ROB) of sandstone CT image in the phase of different stress on the fixed 5 sections are obtained. At the same time the CT number information pertain to different subareas is analyzed. By virtue of the frequency, contour, subarea and extremum of CT number, the beginning position of crack is located on the basis of the time and space information picked up, the criterion of CT number is determined when the crack appears, and the meso-mechanic of damage evolution is studied. Above all, a statistical damage variable is defined, a damage evolutional equation and constitutive equation based on CT number are developed, too.The disposal and quantitative description method of the CT test data based on the image measuring is explored in this paper, which can be widely used in fully analyzing and sufficiently utilizing the image information obtained and pushes the development of the rock and soil mechanics CT experiment forward. All these have certain theoretical meaning and applied value.