Abstract:The acoustic emissions and elastic strain energy decrease of rock specimens with initially random material imperfections in uniaxial plane strain compression were numerically modeled by using FLAC. Beyond the failure of the imperfection that is weaker than the intact rock element, it undergoes ideal plastic behavior, while the intact rock element exhibits the linear strain-softening behavior and then the ideal plastic behavior once failure occurs. As the imperfection number increases, the peak of elastic strain energy decrease rate (elastic strain energy decrease per 10 timesteps) decreases. The steeper the post-peak stress-axial strain curve is, the higher the peak of elastic strain energy decrease rate is. The peak of elastic strain energy decrease rate occurs in strain-softening stage. As the imperfection number increases, the total elastic strain energy decrease has a decreasing tendency. The failure of intact rock elements leads to a rapid increase in the total elastic strain energy decrease. As the exerted axial strain increases, its increasing tendency becomes slow. The numerical rock specimen with initially random material imperfections can better model the actual failure process of rock material, while the homogeneous specimen cannot.

Key words: rock; random imperfection; failure process; acoustic emissions; elastic strain energy; strain-softening; imperfection number