Digital characterization and equivalent mechanical parameters of broken rock mass based on structural characteristics of rock mass

The digital representation, representative elementary volume (REV), and mechanical parameters of broken rock masses are essential foundations for simulating and studying the mechanical properties and behaviors of broken rock masses. Taking the broken surrounding rock of the main powerhouse of the Liyang pumped storage power station as the research subject, an equivalent rock mass model was constructed using equivalent rock mass techniques. Through a series of numerical tests, the REV size and equivalent mechanical parameters of the broken rock mass under various factors were investigated. The results indicate that the REV size of the broken surrounding rock of the main powerhouse, determined based on the equivalent cylindrical rock mass model, is 5 m × 10 m. The broken rock mass with a friction angle of structural planes lower than 30° exhibits brittle failure after reaching the uniaxial peak stress. As the number of fractures within the rock mass increases, the equivalent mechanical parameters of the rock mass show a decreasing trend, and the degree of dispersion of the mechanical parameters increases. Furthermore, the ratio of structural surface trace length to spacing was proposed as a classification criterion for broken surrounding rock, and a range of mechanical parameters for different types of broken rock masses was provided. This study offers important references for the numerical calculations of the mechanical behavior of broken rock masses.