Influence of Superimposed Fracture Angle on the Local Deformation Field of Rock-Like Models with Fractures

ABSTRACT To explore the relationship between the local deformation and overall instability of geological bodies containing fractures, rock-like models were prefabricated with preset fractures inclined at angles of 25°, 35°, 45°, and 60° relative to the loading direction. The internal strain at the tip of the prefabricated fracture and the relative displacement rate on the model surface were observed through embedded strain bricks and digital imaging technology, respectively, revealing the mechanical properties and dynamic evolution laws of the local deformation fields under uniaxial compression in rock-like models with different superimposed fracture angles. The results showed that the greater the superimposed fracture angle of the rock-like model then the greater its peak strength. Moreover, the model required more pressure and time for compaction, which resulted in weaker elastic deformation capabilities. Variations in the local deformation field had a controlling effect on the overall stability of the model. With an increase in the superimposed fracture angle, the variation in the maximum principal strain and the fluctuation range of the local stress deflection angle in the model increased accordingly. In the later stages of loading, models with smaller superimposed fracture angles exhibited a lower relative displacement rate than those with larger angles, and their relative displacement rates gradually stabilized. The rock-like model with a smaller superimposed fracture angle had less internal disturbance under external forces, and the relative displacement rate was more stable, resulting in better stability. In summary, the significant increase and directional deviation of the local strain can be seen as a precursor to overall model instability. The superimposed fracture angles critically govern the transition from elastic deformation to brittle failure, with smaller angles enhancing stability by reducing internal disturbances and strain deflection.