Effects of pore-crack relative location on crack propagation in porous media using XFEM method

In this study, we use eXtended Finite Element Method (XFEM) to simulate the crack propagation in a porous rock. Simulation results showed that if the sample is divided into different partitions, the XFEM can produce reliable results (i.e., crack path and stress intensity factor) similar to experimental tests and analytical solutions. Therefore, we used such a strategy to investigate the crack-pore relative location parameters including porecrack distance (D), size (r) and angle (theta)in an edge model with one pore. Results showed that, by increasing D from 20 to 60 mm the pore is about 14% less destructive and a higher force is needed for crack growth. Also, by decreasing the pore radius from 12 to 4 mm, the required force for crack propagation decreased and the pore is about 10% less destructive. To investigate the effect of pore-crack angle, we defined the minimum angle that a crack deflects to the pore as the deflection angle (theta(d)). Then, theta(d )obtained in 15 different models for a verity of D/r ratios and r. These results were compared to the models containing two pores and an edge crack between them to recognize the more effective parameters in different conditions. Obtained results are summarized as: In a model containing one edge crack and two pores: 1. If D/r ratios are constant and rs are different, the crack path deflects toward the closest pore, 2. If rs are constant and D/r ratios are different, the crack path deflects toward the closest pore. In these two conditions, the pore-crack distance (D) is the dominate parameter. 3. If both D/r ratios and rs are different but the deflection angles are equal, the crack path deflects toward the pore having smallest D/r ratio.