An experimental study of the fracture morphology of marble under dynamic loading

To investigate the fracture morphology characteristics of marble under dynamic loading, the dynamic compression and splitting tests of rock samples under different impact velocities are carried out using the split-Hopkinson pressure bar. The fracture morphology of the rock samples is observed by tungsten filament lamp scanning electron microscope, and the fracture modes of the rock samples under different test conditions are contrastively analyzed. Finally, the fractal dimension is adopted to quantitatively characterize the internal relationship of the fracture morphology and roughness of the rock sample with the impact velocity. The results show that the dynamic fracture of marble is brittle and its basic fracture mode is the intergranular fracture or transgranular fracture. Under the high impact velocity, the fracture patterns of the rock samples become smaller and denser, and the rock powers adhered to the surface increase. Compared with the dynamic splitting test, the fracture degree of the rock sample after dynamic compression is higher, and the proportion of transgranular fracture in fracture pattern is larger. With the increase of impact velocity, the fracture mode of dynamic splitting and compression changes from the intergranular fracture with low energy consumption into the transgranular fracture with high energy consumption, and the fractal dimension value grows correspondingly. However, the fractal dimension value of the dynamic splitting test is more rate-sensitive than that of the dynamic compression test.