The estimation of damage status and fragment size distribution for mining and tunneling applications

THE ESTIMATION OF DAMAGE STATUS AND FRAGMENT SIZE DISTRIBUTION FOR MINING AND TUNNELING APPLICATIONS Abstract Rock failure widely exists in geotechnical engineering, particularly in tunneling and underground mining. Accurate estimation of fragment size distribution not only can ensure the safety and efficiency of engineering projects but is also helpful to save on transportation expenses and avoid costs caused by secondary fragmentation. This research proposes a method to estimate the size distribution of rock fragmentation based on the self-similarity. In this paper, a combined use of fractal theory, elasto-plastic theory and energy conservation theory was adopted. By considering damage energy and size distribution, the fractal damage constitutive model is proposed. In this model, fragment size, damage state and fractal dimension are three main influencing factors. To verify this model, red sandstone was selected as a case study. By fitting the stress-strain curves and quantity-frequency curves, the brittle index and fractal dimension were calculated. Through utilizing the method proposed in this research, the damage status and fragment size of jointed rock mass and collapsed roof in goaf can be estimated. Eventually, implementation of the estimator model would support the attempts towards autonomous operations and vision-based monitoring approaches. Keywords: Fractal theory; Damage constitutive model; Size distribution; Rock fragmentation