| A large number of real rock and model material experiments, numerical simulations on the mixed mode fracture under compression-shear loading had been carried out by scholars at home and abroad. However, due to the discreteness of the test results and lack of research on the influencing factors, also the conventional finite element method has many difficulties to deal with the strong discontinuities, such as the high density mesh on the crack tip, remeshing as the crack grows which is complicated and low efficiency, little satisfactory results were obtained till now.The extended finite element method (XFEM) is the most effective method to deal with strong discontinuity problems. In this paper, a numerical model based on the XFEM was established, the propagation progress of wind crack was simulated, the test results shows:The initial cracking load of wing cracks decreases as the increasing of flaw angle, the propagation load of wing cracks with larger flaw angle is larger then that with smaller ones when wing cracks reach a certain length; The displacement is so small at the beginning of the propagation of wing crack, so the increment step should be suitable.The concept of equivalent normal stress is applied in this paper, theoretical analysis results on the initiation angle of wing crack using sliding crack model showed good agreements with the real model and numerical results, the test results shows:The initiation angle of wing cracks decreases as the increasing of flaw angle; To the closed flaw, the stiffness of filling materials has a influence on the initiation angle of wing cracks but the friction factor has no influence.The propagation progress of wind crack in the experiments on the mixed mode fractures under compression-shear loading and the anchorage effect was simulated in this paper, the results showed that the initial cracking load of wing crack is related to the anchorage stress, anchorage location and anchorage angle.
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