Finite element analysis of rock fracture characteristics under anti-plane shear(Mode III)loading

Finite element method is used to calculate the stresses at the crac k tip in the anti-plane shear rock specimens,with different crack spans(SL),cr ack lengths and specimen thicknesses.The size effect on the stresses at the cra ck tip is discussed.The crack initiation angle and fracture mechanism are studi ed numerically and experimentally.The results show that Mode Ⅲ(anti-plane she ar) fracture is not certain to occur under the anti-plane shear loading.When th e ratio of maximum shear stress to maximum tensile stress,(max (1,is smaller t han the ratio of shear strength to tensile strength,(c (t,the pre-crack is ini tiated and propagate deviating from its original plane.The fracture is of Mode I(tensile).The anti-plane shear specimen with SL0.8 and aw0.2 is suggeste d for realizing the Mode Ⅲ fracture of rock.