Regularities of Plastic Deformation Zone Formation Around Unsupported Shafts in Tectonically Disturbed Massive Rock

In the presented paper, an approach to assessing the size of the plastic deformation zone around a circular cavity intersecting a crushed disintegrated layer in tectonically stressed massive rock is suggested. Fractured rock zones of different quality and spatial configurations are investigated in order to predict the size of dangerous plastic deformation zones or zones of potential rock collapses. The analysis is performed by means of numerical modeling after preliminary verification of the model by in situ and monitoring data. The paper explores the impact of such parameters of the fractured rock zone as the GSI index, the true thickness of the zone, and its inclination angle relative to the plane perpendicular to the axis of the excavation. It was found that with the increase in the thickness and angle of inclination of the fractured rock zone, the size of the hazardous zone in the vicinity of the excavation increases, while with the increase in its strength characteristics, the size of the potential failure zone decreases. According to the results of the study, qualitative dependencies are established, which localize and predict the size of the danger zone, or the potential failure zone in the vicinity of an unfixed excavation.