41 / 2023-05-15 16:20:16

Methods, technical means and study results on rock burst prediction and hazard assessment in underground ore mining.

rockburst hazard, technogenic seismicity, stress-strain state, integrated monitoring, prediction

The problem of predicting and preventing mining impacts during underground mining has been one of the most difficult in world science and mining practice for many years.

With the transition of mining operations to ever deeper horizons and an increase in the volume of worked-out spaces in underground mines, the intensity of dynamic manifestations of rock pressure has significantly increased. Moreover, along with traditional forms, manifestations of mine or technogenic seismicity are increasingly observed. The manifestations of technogenic seismicity indicate the activation of geodynamic processes caused by a destruction of the natural balance under the influence of mining operations.

The prediction of the rockburst hazard in such conditions is a very difficult task, since it is necessary to study not only individual, local sections of the massif, but the entire mining system as a whole, including its tectonic structure in conjunction with the regional geodynamic situation. In these conditions, for the control and effective management of rock pressure, it is necessary to use a set of theoretical and instrumental methods, which can be grouped into the following 3 blocks. At stage 1, geodynamic zoning of the deposit is performed, the physical and mechanical properties of rocks and ores are determined, the parameters of stress fields and other characteristics of the rock mass are evaluated. The next important block of research consists in the construction of mathematical models, with the help of which patterns of changes in geomechanical fields and processes at various stages of mining are revealed.

Obtained by us results of numerical modeling of the stress-strain state of the developed rock mass of the Nikolaevsky and Yuzhny polymetallic deposits, the Yuzhno-Khingansky manganese ore deposits and a number of others allowed us to identify important patterns of stress fields formation and identify potentially rockburst-hazardous elements of mining.

For a more reliable prediction of dangerous geodynamic phenomena, it is necessary to use special instrumental methods and technical means. The most reliable predictive estimates of rock burst hazard can be obtained by applying various complementary methods combined into a single system of integrated geomechanical monitoring. Such systems were created by us at geodynamic polygons in Transbaikalia and the Eastern Primorye of Russia in the Streltsovsky and Dalnegorsky ore regions.

The integrated geomechanical monitoring system includes microseismic and geoacoustic stations, strainmeter, including a high-precision laser interferometer, devices for local assessment of rockburst hazard. The devices and equipment used are integrated into a single observation network, in which time synchronization is provided during data registration by all measuring instruments included in the system. The integrated monitoring system allows you to register and analyze a wide range of parameters of time- and space-varying geophysical fields, including their energy, spectral and other characteristics.

According to many years of research results, it has been established that an important feature of the behavior of rock mass prone to a rockburst is the formation of active zones (potential foci of geodynamic phenomena) in it, within which the process of clustering of sources of micro-destruction occurs. We have developed an original technique for the identification and analysis of emerging foci, based on the theory of random graphs using the established connectivity component.

In recent years, we have increasingly observed the manifestation of a trigger effect at rockburst hazardous mines, when geodynamic phenomena are initiated by relatively weak impacts from technological explosions or other sources of seismic waves. The study of the trigger effect opens up opportunities for the development of effective methods to reduce the impact hazard (methods of "controlled" unloading).

The results of our research have made it possible to develop regulatory documents regulating mining operations at a number of ore deposits in the Far Eastern region of Russia that are hazardous and prone to rockburst. The necessary level of safety is ensured by the use of effective methods and means of assessing and controlling the rockburst hazard and reasonable measures to manage rock pressure and reduce geodynamic risk.