An evaluation method for geological dynamic environments of mines and the classification of mines subjected to rock bursts

The occurrence of dynamic disasters in mines, such as rock bursts, is affected by multiple factors and is the result of the coupling of the natural geological dynamic environment and mining engineering disturbances. The characteristics of rock bursts including their time, space, and intensity are related to the regional geological dynamic environment of mines. Different coal fields, mining areas, and mines have different regional geological dynamic environments. Accordingly, some coal mines do not have a geological dynamic environment of rock bursts, while some are subjected to different types of rock bursts. This study proposed an evaluation method for the geological dynamic environments of mines and constructed an evaluation index system. The study of geological dynamic environments mainly focuses on the effects of the dynamic process of external geological bodies on rock bursts under natural geological conditions. Therefore, it was determined that evaluation indices of geological dynamic environments consisted of influencing factors such as the tectonic contrast of tectonic concaves, tectonic movement of fault blocks in mine areas, fault structures, tectonic stress, mining depth, the structural characteristics of overlying strata, and the criteria for the study area and its adjacent areas. Then, different quantitative evaluation values of these influencing factors were determined according to the degrees of their influences on mines. Afterward, the quantitative evaluation results were integrated to determine whether a mine has a geological dynamic environment of rock bursts according to the following criteria: (1) a value of the integrated evaluation index (n) of 0-0.25 indicates a mine has not a geological dynamic environment of rock bursts; and (2) an n value of 0.25-0.5, 0.5-0.75, and 0.75-1.0 indicates that a mine has a geological dynamic environment of weak, moderate, and intense rock bursts, respectively. Based on the evaluation indices of the geological dynamic environments of mines, the geological dynamic environment and energy for the occurrence of rock bursts in engineering geological bodies can be determined. Then, the mines can be classified as mines free from rock bursts, mines subjected to rock bursts, or mines subjected to severe rock bursts. With the Shuangyashan-Jixian coal field at the margin of the Suibin Depression Basin as an example, this study analyzed the geological dynamic environment of the Jixian coal mine in the Shuangyashan mining area and determined that the Jixian coal mine has an n value of 0.67. This result indicates that the Jixian coal mine has a geological dynamic environment of moderate rock bursts and is a mine subjected to rock bursts. As verified by the results of this study, the geological dynamic environment is a critical influencing factor and a basic energy condition inducing dynamic disasters of mines, such as rock bursts.