The initiation and growth of crack are important features of rock fracturing and burst. Microseismic monitoring and sound reflection technique are main methods to monitor the initiation and growth of crack Howecr, it is difficult to apply tomography to study crack initiation and growth using conventional methods. Electrical Resistivity Tomography (ERT) is usually used to image geological body and metal mine, and has been proved to be useful. The resrstivity of crack is higher than surrounding rock, which is the essential condition to use ERT technique to monitor the crack. In this paper, Finite Element Method (FEM) based on Preconditioning Conjugal Gradient (PCG) algorithm is used for the first time to model the ERT for crack growth Jacobian preconditioning matrix is the key technique to solve the large linear system in FEM, by which the calculation speed is greatly improved. In order to precisely locate the crack, geophysical inversion technique (smooth least-squares method) is used to calculate the distribution shape of crack. The result of 2D inversion is consistent with the process of crack growth. Throughout this study, it is concluded that it is feasible to monitor crack growth with ERT technique.
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