Study on the Mechanical Behavior and Constitutive Model of Layered Sandstone under Triaxial Dynamic Loading

In construction engineering, rock is an important building material. During the construction process, layered rock masses are typically subjected to varying dynamic load disturbances under triaxial loads. It is thus essential to investigate the mechanical response of layered rocks under various disturbances of the triaxial loads. By using a three-dimensional SHPB, triaxial dynamic compression tests with various impact dynamic load disturbances and identical triaxial static loads were carried out on sandstones with differing bedding angles. The impact pressures were 0.8, 1.2, and 1.6 MPa, and the bedding angles were 0°, 30°, 45°, 60°, and 90°. The results showed that the ductility of the sandstone considerably increased under triaxial static loading. With the increasing bedding angle, the sandstone’s dynamic strength and coupling strength first declined and subsequently rose. As the impact pressure increased, the reflective energy ratio, peak strain, and dynamic growth factor of the sandstone essentially rose progressively. The bedding angles and dynamic loads had a major impact on the damage pattern of the layered sandstones. Additionally, a constitutive model considering bedding angle, dynamic load, and static load was established and verified. The constitutive model was able to accurately characterize the dynamic behavior of the rock under load disturbances.