Study on the stress field concentration at the tip of elliptical cracks

Abstract The holes and defects in rock materials have a great impact on the mechanical properties failure mechanism of rock, cracks often appear form flat ellipses natural mass, current research is still insufficient. For this purpose, based Particle Flow Code (PFC) discrete element particle flow program, numerical prefabricated fractured samples with ratios long short axes elliptical fractures being 5, 7.5, 10, 12.5, 15 were simulated order to obtain strength characteristics, stress concentration characteristics at tips uniaxial compression test. results test simulation show that: (1) When models crack damaged, initial occurred end axis crack, penetrated up down from surface wing both ends axis, gradually formed macro-crack, secondary extended near crack. (2) With increase : b fracture, elastic modulus decreased, Poisson’s ratio increased, total number micro-cracks decreased. (3) solutions factor k obtained by simulations tip increased ; it was highly consistent variation law analytical solution calculated theory ellipse. an important reason for cracks. Study will be very useful significant.