ABSTRACT
Geodynamic risks presuppose breakdown risks in technological processes and engineering objects mining working, oil wells, pipelines and other communications, buildings and constructions, impact on people’s and animals’ health related to dynamic processes in the upper layer of the earth crust and often caused by natural phenomena as well as interaction of both natural and anthropogenic factors. The most challenging problems with geodynamical safeguarding occur in the old mining regions where the natural geodynamical balance of rock mass is disturbed.
The study evidences that active faults and phenomena related to them (geomechanical, hydrogeological, geoelectrochemical, etc.) contribute the most to geodynamical hazards. The hypocenters of most earthquakes and rock-tectonic bursts, more than two third of rock bursts and sudden gas coal outbursts in mines, up to half trunk pipelines breakages, more than half accidents in city underground communications, not less than a quarter of development of karst and gullying events, landslides, etc. account for the fault zones, comprising the first percentage of the Earth surface total area.
Manifestations of faults activity and fault zone properties, affecting mining, hydrocarbons extraction and other industry-related objects are considered in detail. Different fault zones are classified by risk type and level. It is shown that both mining and hydrocarbons extraction is affected by the most compressed spans of faults where they are closed joints in rock mass, notable for extreme strength and burst-hazard. Another relevant type of fault zones are split and tension zones, affecting the risks of above-ground and buried communications breakdowns; breakouts, rock falls and excessive water inflows occur when mining. Geological factors to identify fault zones of different types are described. It is proved that although mining alters the stress pattern of rock mass, most of hazards account for the faults already existing in the rock mass with abnormal tectonic stresses.
Three stages of hazardous dynamical events prevention are specified: geodynamical zoning and risk assessment, geodynamical survey, measures to reduce hazards. Geodynamical zoning technique which allows to identify potentially hazardous zones at early stages is considered in detail. The technique involves active faults identifying, block structure reconstruction, calculation of stress pattern with the help of mathematical and physical modeling, direct and indirect estimates of rock tension; exploring mechanisms of dangerous geodynamical events both above ground (pipelines breakages) and underground (rock and tectonic bursts). Techniques of comprehensive geodynamical survey in mines and shafts are considered, including different types of survey—seismic, deformational, acoustic, electro-magnetic, etc., and techniques of prognosis and prevention of dangerous events as well.
By way of illustration rock bursts prognosis in mines, open-pit slopes and benches stability analysis, mineral deposits locating and oil production stimulation and potentially breakage zones in trunk pipelines and underground communications are considered in the study.
