Failure behavior of the surrounding rock of jointed rock masses in a gold mine under blasting impact disturbance

Blasting impact disturbances have an important influence on the safety of underground engineering openings. In this article, in-situ stress measurements and a structural plane investigation were conducted in a gold mine, and a numerical model of roadways through jointed rock masses was established using 3DEC software. The instability and failure characteristics of the surrounding roadway rock with dominant joint planes under blasting impact disturbance as well as the influence of the burial depth, impact stress wave peak, and stress wave delay on the surrounding rock stability were analyzed qualitatively and quantitatively. The results showed that the in-situ stress increased linearly with depth, and the stress level was relatively high. The two identified groups of dominant joints were interlaced, with inclinations of 234.24 degrees and 327.47 degrees. Three failure modes in the surrounding rock, i.e., tensile-shear failure, tensile failure, and shear failure, were determined and occurred in different areas around the roadway, while shear failure was dominant. Moreover, when the burial depth increased from 1200 to 2000 m, the maximum vertical displacement and the maximum horizontal displacement around the roadway increased by 14.07-84.92% and 25.04-239.32%, respectively. As the stress wave peak increased from 5 to 25 MPa, the maximum vertical displacement and the maximum horizontal displacement around the roadway increased by 17.64-54.77% and 18.62-107.30%, respectively. The greater the burial depth and stress wave peak was, the more was noticeable the deformation of the surrounding rock. With increasing stress wave delay (i.e., the frequency decreased from 40 to 5 Hz), the damage degree of the roof and right side of the roadway had no significant change, the damage degree of the floor was weakened overall, and the damage degree of the left side was weakening at first and then increased, showing complex failure characteristics. Essentially, the macroscopic failure of the surrounding rock was the cumulative reflection of the initiation and propagation of microcracks in the surrounding rock.

Automated summary

This study analyzed the influence of blasting impact disturbances on the stability of surrounding rock masses in jointed rock roadways through in-situ stress measurements and numerical modeling. The results showed that burial depth, impact stress wave peak, and stress wave delay significantly affected the deformation of the surrounding rock.