Abstract
The paper discloses that geological faults and phenomena associated therewith are the main risks of mining. The phenomena of fault activity and specific features of near-fault zones, determining their impact on the stability of mine workings and other man-made objects are discussed in detail. Different sections of faults are classified according to the degree and types of risk. The main attention is paid to the most stressed zones, where the fault is a closely spaced crack in the rock, characterized by specific strength and rock-bump hazard effect. The paper discloses that although mining operations change the stress-strain state of the massif, nonetheless, most of hazardous situations and geodynamic phenomena during excavation occur in tectonically stressed zones that already existed in the massif. In these areas, man-made overload during mining results to the formation of extremely stressed geodynamically hazardous zones. Thus, geodynamic zoning, which includes the identification of faults and block structure, assessment of their activity, as well as reconstruction of the stress-strain state of both the blocks and the near-fault zones, is the key method for assessing risks of geodynamic phenomena.
Highlights
In a broad sense, geodynamic hazard involves all the risks of disturbing engineering facilities, mine workings, buildings and structures, affecting human and animal health, etc., associated with dynamic processes in the top layer of the earth's crust - earthquakes, karst, erosion, large deformations, radiation, gas emanations, etc
Faults are considered as a serious cause of accidents, especially of rock bursts, but not necessarily the main one
It is near tectonic disturbances where the most of accidents of various types occurs
Summary
Geodynamic hazard involves all the risks of disturbing engineering facilities, mine workings, buildings and structures, affecting human and animal health, etc., associated with dynamic processes in the top layer of the earth's crust - earthquakes, karst, erosion, large deformations, radiation, gas emanations, etc. 3. The nature of change in all indicators discloses a significant difference in the physical and stress state of the coal seam in the near-fault zones of the two types of discontinuous faults. Mining operations significantly change the stress-strain state of the massif, most of hazardous situations and geodynamic phenomena during excavation occur in tectonically stressed zones already existed in the massif. 4) in unloaded zones can be compared with the hazard level of stressed zones with a ratio of ϭ1 with a uniaxial compressive strength in the range of 0.2–0.3 It is pronounced in the form of a decrease in the stability of the roof of the workings, vertical exposures (including a longwall face), rock inrush, balm stones, etc., increased gas release, as well as sudden outbursts of gas, coal and rock from the walls of the workings. A special hazard in such zones is associated with increased water inflows, which can result to siltation of a long-wall and the risk of losing expensive mining equipment
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