DEM modeling of large-scale triaxial test of rock clasts considering realistic particle shapes and flexible membrane boundary

This paper presents a novel framework for the discrete modeling of the large-scale triaxial test of rock clasts, considering both the realistic particle shapes and veritable flexible boundary condition. First, real-shaped particle models for the tested rock clasts are precisely reconstructed using the close-range photogrammetry technique. The rubber membrane was modeled by a series of bonded particles. Then, the laboratory procedures of the triaxial test, i.e., sample preparation, isotropic compression, and shearing, are reproduced in the DEM simulations with consideration of the veritable confining boundary. To ensure more reliable numerical results, a systematic DEM calibration framework is established to determine the modeling parameters based on a series of calibration experiments, including tensile test, suspension test, clast-membrane sliding test, and large-scale triaxial test. Finally, the proposed method is applied to investigate the effects of confining pressure on the macro- and micro-mechanical behaviors of rock clasts. The presented works lay a foundation for further studies on revealing the mechanisms of the conventional triaxial test, e.g., the effect of end restraint and rubber membrane. Moreover, the proposed systematic framework for calibration of modeling parameters can be applied to precisely capture the real mechanical properties of various types of granular rock-like materials in DEM simulations.