Creep Behavior Modeling of a Marble Under Uniaxial Compression

Axial strain–time curves for a marble sample were obtained by performing uniaxial compression tests with step loading. Axial strain rate–time data points were then obtained from the axial strain–time curves. One power function and one exponential function were selected from the literature to fit the experimental creep data. Based on the characteristics of the plotted axial strain rate-time data points, one power function and one exponential function were proposed as possible functions to model the creep data. By comparing the goodness-of-fit of the aforementioned four functions through regression analysis, it was found that the two exponential functions fit the experimental creep data better than the two power functions. The two exponential functions showed very close goodness-of-fit levels on the experimental data. The proposed exponential function has only two parameters compared to that of the exponential function in the literature which has four parameters. Therefore, the proposed exponential function is selected as the creep model of marble. This model is also related to a built-up combined spring-dashpot model known as the generalized Kelvin model. The model parameter values of the generalized Kelvin model are then calculated by the parameter relations that exist between the generalized Kelvin model and the proposed exponential function.