Finite element analysis of plane shear(Mode II) fracture mechanism of brittle rock at high temperature

Finite element method is used to calculate the crack-tip stresses of rock specimens under plane compression-shear loading in order to study the mechanism of plane shear(Mode II)fracture. Numerical results show that both the tensile and shear stresses exist at the crack tip and the ratio of maximum shear stress to maximum tensile stress,tau(max)/sigma(1),is about 3-6. Since the additional compressive can restrain tensile stresses at the crack-tip, tau(max) can easily reach its limited value before sigma(1) and cause plane shear(Mode H)fracture. Plane shear-box test is a potential method for obtaining Mode II fracture of rock and determining Mode H fracture toughness K-IIC of rock.