A three-field phase-field model for mixed-mode fracture in rock based on experimental determination of the mode II fracture toughness

Abstract In this contribution, a novel framework for simulating mixed-mode failure in rock is presented. Based on hybrid phase-field model fracture, separate variables are introduced tensile (mode I) and shear II) fracture. The resulting three-field problem features length scale parameters mode I II cracks. contrast to the classic two-field approaches, it can thus account different strength of rock. two equations implicitly coupled through degradation material elastic equation, three fields solved using staggered iteration scheme. For its validation, calibrated types rock, Solnhofen Limestone Pfraundorfer Dolostone. To end, double-edge notched Brazilian disk (DNBD) tests performed determine fracture toughness. numerical results demonstrate that proposed able reproduce crack patterns observed DNBD tests. A final example uniaxial compression test rare drill core demonstrates capture complex, 3D when with correct