Three-stage damage constitutive model and parameter inversion of rubber concrete under triaxial compression

Investigating the mechanical properties of waste tire rubberized concrete is critical for ensuring engineering safety throughout construction and operation. An accurate constitutive model is essential not only for characterizing the material’s mechanical behavior but also for reliably predicting its stress-strain response during deformation and failure. In this study, conventional triaxial compression tests were conducted on concrete with varying rubber replacement ratios (Q) under different confining pressures to evaluate their effects on mechanical properties. Concurrently, acoustic emission (AE) monitoring was employed to capture the damage evolution during the tests. Based on the experimental results, the increasing rubber replacement ratio significantly enhanced the Poisson’s ratio while reducing the internal friction angle, cohesion, and elastic modulus. By synthesizing AE counts with stress-strain curve characteristics, the deformation process was delineated into three distinct stages: compaction, elastic, and damage evolution. This segmentation served as the foundation for developing a three-phase statistical damage constitutive model for concrete under triaxial compression. The model parameters were determined via differential methods, and a comparative analysis confirmed the model’s capability to accurately forecast the stress-strain behavior. Furthermore, the sensitivity of the constitutive parameters, F 0 and m , regarding their influence on stress and damage evolution, was thoroughly analyzed.