Numerical investigation of the effect of scale, loading rate, and lateral load on the stress-strain behavior of rock under pressure

In this study, uniaxial and biaxial compression tests were simulated to assess the impact of sample scale - both dimensions and shape - along with the rate and nature of loading on the strength behavior and deformability of a limestone rock specimen. For this end, the finite difference method (FDM) using FLAC code was employed. The compression test simulations utilized an innovative technique based on the model's equilibrium principle during loading, mimicking static loading conditions in reality. This approach facilitated systematic control of axial and lateral loads on the model, effectively preventing abrupt violent failure. A series of two-dimensional (۲D) models were subjected to varying loading conditions to appraise the stress-strain behavior of the computational models. Numerical results show that changes in the model's shape and dimensions affected the compressive strength of rock models. Here, an increment in the width-to-length ratio of the model led to enhanced compressive strength. Similarly, an increase in the loading rate also increased the uniaxial compressive strength of the model. Also, by applying and augmentation of lateral pressure in the biaxial compression test further increased the rock model's compressive strength. Hence, rocks under pressure demonstrate scale-dependent behaviors, exhibiting varying strengths under different loading conditions.

Keywords:

Compressive strength , Stress-strain behavior , Rock , Numerical modeling , Finite difference method (FDM)