STUDY ON THE FREEZE-THAW DAMAGE CHARACTERISTICS OF SKARN BASED ON CT THREE-DIMENSIONAL RECONSTRUCTION

To study the mesoscopic damage evolution characteristics of skarn under freeze-thaw cycles, based on CT technology, the skarn samples under freeze-thaw action were scanned by CT, and the image data of skarn were segmented by Avizo software. The digital model of the three-dimensional structure of skarn was established, and the evolution law of the internal structure of skarn during the freeze-thaw cycle was quantitatively analyzed. The box dimension algorithm calculates the fractal dimension of the pore structure under freeze-thaw conditions. The relationship between fractal dimension, pore volume fraction, and freeze-thaw cycles was studied. According to the statistical results of the pore size distribution of skarn, the change characteristics of pore structure in the rock under the influence of freeze-thaw were studied. Based on the theory of rock damage mechanics, the damage variable of skarn was defined using the concept of the effective bearing zone, and the freeze-thaw damage evolution of skarn was studied. The results show that the three-dimensional reconstructed model can directly show each medium's mesopore structure and spatial distribution. There is a positive correlation between pore volume fraction and fractal dimension under freeze-thaw conditions. The fractal dimension satisfies the exponential growth law. The skarn damage variable increases with the increase of freeze-thaw cycles, which is consistent with the development trend of pore structure. The exponential function can better reflect the damage evolution of skarn under freezing and thawing.