SCANNING ELECTRONIC MICROSCOPE TESTS FOR ROCK MICRO-RUPTURE MECHANISM AND FRACTURE CHARACTERISTIC OF PHYLLITE

Macroscopic fractures of rocks are strongly linked to their microstructures and micro-defects.It is one of difficult problems of rock fracture mechanics to establish more intuitive relationship between rock microscopic mechanism and macro rupture.This paper uses the sericite phyllite and siliceous plate phyllite of Middle Devonian series on upriver of Jinsha River as the research object.The micro-rupture properties of rock are judged and the relation between the form and mechanism of phyllite micro-rupture and mineral component is revealed through scanning electronic microscope and mechanical tests.The sericite phyllite shows micro-scratch micro-fracture fracture which is a typical micro-brittle shear.The forms of micro-fracture have both pull-off rupture caused by intergranular fracture and the micro-shear rupture,belonging to the micro-fracture mechanism of the coexistence of the tension and shear fracture.The physical meaning of rock fracture is analyzed with the combination of mechanic characteristics of macroscopic fracture.The evidence is acquired to establish the link between rock micro-rupture mechanism and macroscopic fracture analysis.