Abstract: According to the uniaxial cyclic loading and unloading test results of sandstone with precast fissures， the effects of fracture geometric parameters on elastic modulus of specimens were investigated. Using PFC^2D code， the relationship between crack development status and elastic modulus of specimens was analyzed. The research results show that: with the increase of cycle numbers， the elastic modulus of most specimens shows a strengthening phenomenon， and the first loading/unloading cycle has the most significant strengthening effect on the elastic modulus， which is related to the internal meso-structure; while the elastic modulus of a few specimens shows a weakening phenomenon; and combining with the PFC^2D code simulation， the weakening phenomenon is closely related to the crack development status.

Key words: objective, interval particle, intervalcyclic loading, precast fissures, elastic modulus, particle flow code