A Core Damage Constitutive Model for the Time-Dependent Creep and Relaxation Behavior of Coal

The creep and stress relaxation behaviors of coal are common in mining. unified constitutive model is suitable to describe predict both the evolution characteristics rocks. generalized Kelvin core element for traditional improved component models reflect nonlinear relaxation. In this paper, an damage model, which could relation evolution, was established based on a comparison models, responding equations (creep equation) at constant stress/strain were deduced. Then, validated uniaxial compressive multistage test results coal, showing that curves had great accordance with experimental data. Moreover, comparisons accuracy, parameter meaning, popularization among hardening-damage fractional derivative further discussed. showed parameters clear brief physical significances. also popularized depict time-dependent other rocks, accuracy.