Excavation disturbance and stability of short-distance roadway with high stress and soft rock mass

According to the excavation and stability problem of short-distance roadway with high stress and soft rock mass, theoretical derivation, numerical calculation and field monitoring are made. At first, the propagation law of disturbance stress in excavation blasting and its stability influence on the surroundings of short-distance roadways or chambers are analyzed based on the geological and construction conditions of deep roadway in one mine. An attenuation equation for the disturbance waves in rock mass is given. And then, the FLAC software is used to numerically analyze different excavation projects including lengths of one blasting and excavation steps. The results show that the induced deformation in the excavation process can directly affect on the surrounding rock of the adjacent roadways or cambers under the action of dynamic load (development blasting), and stress release area is greater. The deformation of the whole roadway increases because of many disturbance times when the length of one blasting is smaller, but its initial velocity is less, while vice versa. Finally, the way of field monitoring is adapted to analyze the excavation disturbance to constructing roadway. The results show that the greater degree area of blasting disturbance is about 10～20 m of heading face of the nearby excavated roadway to two roadways with a distance of20 m. But for this project, it is about 25 m. The disturbance area includes failure zone, greater effect degree zone and less effect degree zone according to different degrees. The failure zone and the effect zone lie in the area of heading face with a distance of 30 m.