Ensuring Seismic Safety of Underground Mines During Blasting Operations in Combined Surface-Underground Deposit Development

At present, there are no standard methods for assessing seismic safety of underground mines during blasting on the earth’s surface. The need for such assessments arises when underground mines are located near open-pit coal mines, when the mine fields development is continued into the open pit, and when open surface coal mines use highwall miners. The issues of assessing seismic safety can be complicated by the lack of experimental data on vibration parameters, for example, if the answer is already required at the stage of new mines designing. The paper also provides an analysis of experimental data, including the results of monitoring the state of underground mines during seismic impacts of varying degrees of intensity. It is shown that the spread of the observed PPV, at which local damage or deformation of the underground mines has taken place, attains high values. In the absence of such data for underground mines in specific mining and geological conditions, it is recommended that the maximum allowable PPV vпр be assigned taking into account the class of underground mines and the type of support. At the same time, it is noted that the recommended vпр values given in the literature relate to the openings that were driven in the solid without geological disturbances and anomalies; not deviating from regulatory requirements regarding the state of workings; in the absence of danger of groundwater breakthrough; in the absence of danger of gas-dynamic phenomena, and other negative factors. If this is not the case, according to the requirements of the Federal norms and rules of industrial safety, the seismic safety distance should be increased by 2 times. This requirement is equivalent to multiplying the maximum permissible vibration velocity by a decreasing coefficient k=2b, where the power of two is the regression parameter b obtained from the experimental data processing.