An improved strain-softening model for Beishan granite considering the degradation of elastic modulus

Abstract

During the failure process, granite always exhibits strain-softening behavior and confining pressure-dependent effect. Based on triaxial cyclic loading and unloading compression tests, the evolutions of cohesive strength, internal friction angle, and elastic modulus with axial plastic strain and confining pressure were obtained. The results show that both the cohesive strength and the internal friction angle first increase and then decrease with an increase in the axial plastic strain. Meanwhile, the elastic modulus increases with an increase in the confining pressure and decreases with an increase in the axial plastic strain. Considering the evolutions of the cohesive strength, the internal friction angle and the elastic modulus, an improved strain-softening constitutive model was proposed. The proposed model was further embedded in the Fast Lagrangian Analysis of Continua (FLAC) procedure, based on which the conventional triaxial cyclic loading and unloading tests were simulated. The simulated results have shown a good agreement to the experimental results.