As a naturally heterogeneous material, the mechanical behavior of rock mass is predominantly governed by its internal fractures. Among these, cross-cutting cracks exhibit notably distinct mechanical responses and energy dissipation mechanisms compared to single fissures, primarily due to their complex geometric configurations. In this study, uniaxial compression tests combined with Digital Image Correlation (DIC) technique were conducted to systematically investigate the mechanical properties and energy dissipation mechanisms of sandstone specimens containing cross-cutting cracks with varying inclination angles. The results demonstrate that the presence of cross-cutting cracks significantly deteriorates the mechanical performance of sandstone: both the peak strength and elastic modulus generally decrease with increasing crack angle, and a remarkable strength reduction of 60.15% is observed in specimens with 150° cracks. Furthermore, the crack inclination angle plays a controlling role in the energy dissipation mechanism. The failure of specimens with 30°-60° cracks is dominated by the abrupt release of accumulated elastic strain energy, exhibiting typical brittle characteristics. In contrast, the failure of specimens with 120°–150° cracks is characterized by a dissipation energy-dominated progressive process, where the energy dissipation ratio at peak stress increases significantly from 11.66% for the 30° specimens to 48.76% for the 150° specimens. Finally, the evolution of strain fields captured by DIC reveals that the crack intersection zone acts as the core area for energy dissipation and strain localization, controlling the coalescence process of macroscopic fracture surfaces and considerably reducing the overall bearing capacity of the specimens. This study elucidates the energy dissipation mechanism of cross-cutting cracked sandstone and its control effect on the failure mode, providing both theoretical and experimental foundations for stability assessment of fractured rock masses in engineering practice.

The stress–strain characteristics of compressed sandstone are affected by many different factors. The study on the evolution law of the strain field of compressed sandstone is of great significance for disaster prediction and warning during the construction process of geotechnical engineering. In this paper, uniaxial compression tests of red sandstone of 100 mm height and 50 mm length and width were carried out under the conditions of (1) different loading rates, (2) different particle sizes and (3) different inclination angles of prefabricated fractures. Stress–strain curves corresponding to different conditions were presented, the evolution of strain field on the sample surfaces was analyzed with the help of Digital Image Correlation technology and the relationship between the stress–strain curves and the strain field was preliminarily given. This study may be helpful for obtaining a deeper understanding of the deformation and failure mechanism of sandstone under uniaxial compression.

Fractured rock masses are ubiquitously distributed in deep underground excavations, slope engineering and mining operations. Their failure and instability triggered by impact loads including blasting, seismic events and rockbursts pose a critical hazard to engineering safety. In this study, sandstone specimens with prefabricated fissures at five representative dip angles (0° to 90°) are prepared and subjected to split Hopkinson pressure bar (SHPB) impact tests. By integrating X-ray diffraction analysis, fragment sieving, fractal theory and scanning electron microscopy observation, the regulatory effects of fissure dip angle on the dynamic mechanical properties, energy evolution, fragmentation fractal behavior and mesoscopic failure characteristics of sandstone are systematically explored. The results demonstrate that the fissure dip angle exerts a significant monotonic regulatory effect on the dynamic mechanical performance of sandstone. The strength degradation induced by pre-existing fissures becomes more pronounced with decreasing dip angle, and the 90° vertical fissure exhibits the weakest weakening effect. The evolution of impact energy can be divided into four stages. As the fissure dip angle increases, the proportion of reflected energy decreases monotonically, while the proportions of transmitted energy and absorbed energy increase monotonically. The particle size distribution of crushed sandstone presents favorable self-similar fractal features, and the fragmentation degree is positively correlated with the fissure dip angle.This study reveals the dynamic failure mechanism of sandstone governed by fissure dip angle and establishes multi-scale correlations. The findings can provide theoretical and experimental support for dynamic stability evaluation of fractured rock masses, blasting parameter optimization and geohazard prevention and control.