Abstract: Contact compression test was conducted on natural limestone particles from Lianghekou to study the mechanical behavior and fractal characteristics of contact damage of irregular rock particles. The micro-morphology of particles was characterized by surface fractal dimension, roughness and undulation. The study revealed that the first damage force decreased with the increase of initial fractal dimension; the fractal dimension of particles in local contact range decreased after loading, which implied the influence of micro-morphology of rock particles on mechanical behavior of contact damage. Furthermore, the strain and displacement on specimen surface were traced dynamically by non-contact digital imager, which revealed the changes of strain and displacement in the whole process of particle contact test. The result shows that local stress level is much higher during contact compression between irregular rock particles. The contact damage first appears in local contact zone.

Key words: irregular limestone particle, contact damage, micro-morphology, fractal dimension, mechanical behavior