Study on physico‑mechanical characterization of rock-like material with bedding planes under coupled static and dynamic cyclic loadings

Underground rocks are often subjected to seismic waves and blasting excavation, which cause significant changes in physical and mechanical properties. Due to the bedding plane, the mechanical properties of layered rocks with different dip angles become particularly complex under dynamic disturbance. To investigate the damage mechanism of layered specimens under coupled dynamic and static loading, dynamic disturbance tests were conducted on rock-like material with bedding planes. The results show that the cycle times (C) negatively correlate with the peak load. The linearity of the fit is high, with R² values above 97%. As C enlarges, the loss ratio R_l significantly increases, and the peak load decreases linearly. The strength of the layered samples varies in a "U" shape with the dip angle (θ) for the same dynamic disturbance. The damage patterns were divided into matrix damage (Mode I) and damage along the bedding plane (Mode II), as well as mixed damage forms (Mode III). When θ = 0°, the damage pattern is mainly Mode I. When θ = 22.5°, 45° and 67.5°, the damage form is Mode III. While Mode II dominates the damage pattern of θ = 90°. The characteristics of the acoustic emission source manifest that the specimen tended to expand the damage from the end to the middle as the axial load increased. The damaged surfaces, identified by high energy level damage, closely matched the macroscopic cracks.