Evolution of fracture and failure state characterization of coal based on CT scanning
To characterize the failure state of coal based on the crack evolution characteristics,the test of coal samples under conventional triaxial compression was carried out by the compu-ted tomography(CT)technology.The internal three-dimensional(3D)crack visualization model was reconstructed,and the crack distribution and characteristic parameters were ana-lyzed.Finally,the failure state characterization index Ti(T)was defined based on crack area of the section,and the accuracy and reasonableness of the index were examined.The research results show that:With the axial strain of coal increasing,the crack area and fractal dimension of the section in coal with initial crack decrease at first and then increase,while those of the section without initial crack first remain unchanged and then increase.Ti decreases or remain unchanged at first and then increase in the process of coal instability and failure,and the change range is larger than that of the traditional damage variables,which can more accurately quantify the failure degree of the coal section.With the axial strain of coal increasing,T shows the law of decreasing and then increasing,which is in highly consistent with the 3D crack vol-ume change of the coal.
CT scanningcoalfracture evolutionfailure state characterization index
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