Study on microscopic damage features of coal-rock based on CT scanning

In order to study the image fractal dimension of each scanning section and the variation law of the porosity before and after the loading on the coal-rock,the industrial CT detection technology and the triaxial loading test system were applied to the CT scanning observations on the initial coal-rock and the loading damaged coal-rock under the triaxial condition. An analysis was conducted on the density distribution images of the coal-rock CT sections and the dynamic failure process of the coal-rock under the role of the loading. The study results showed that the fractal dimension and porosity of the coal-rock before and after the failure of different section were different in variation. Under the same stress state,the different section of the coal-rock would have different damage expansion features. Under the role of the loading,the damage evolution of the coal-rock would be a localization and inhomogeneity. With an analysis on the density curve of the coal-rock grey probability,a multimodal distribution occurred in the curves was obtained and could explain the multi damage factors existed in the coal-rock. A single protruding peak existed in the curves could explain one factor in the leading position of a factor. The test results and the coal-rock dynamic damage process combined with the deformation damage features of the coal-rock and with the selection of the suitable damage parameters were applied to establish a damage constitutive model of the coal samples under the role of the loading. The results showed that the theoretical curve and the test curve could be well fitted.