Abstract
According to the analysis conducted on the cases involving such casualties, some workers were either killed or seriously injured when they inserted detonators and blasts into boreholes and mounted a steel arch support in a cutting face. For the purpose of evaluating the mechanism of rock fall at tunnel cutting face, this paper performed experimental tests that involved blasting to excavate a model ground of tunnel cutting face and then analyzed the stress state in the cutting face by using Discrete Element Method (DEM) simulation. In conclusion, the tensile stresses were generated at the bonds between rocks around the cutting face. Moreover, these tensile stresses remained even when the action of gas expansion due to blasting has completely finished. Therefore, it is suggested that the tensile stress opens cracks between the rocks while the stress disappears, after which the gravity acting on rock loosens it and finally causes rock fall.
