Application of roof bolting to reduce water inflow into mine workings during the crossing of tectonic faults

In this work, the problem of water inflow reduction in Ukrainian coal mines, which are distinguished by difficult hydrogeological conditions, was considered. A numerical study of the change in water inflow into a mine working when it crosses a tectonic fault was carried out. The cases when the permanent working was supported by frame supports and roof bolts were considered. The calculation of stress fields, zones with inelastic deformations and coefficients of permeability, which depend on the stress state and takes into account tectonic and natural permeability of the rocks, was performed. The results of calculating the water pressure and water inflow into the mine working in all considered cases are presented in the article. Analysis of the calculated data showed that a disturbed area, which covered water-bearing ricks, was formed in the roof of the mine working with the frame support. Within this area, water can move towards the contour of the mine working. The filtration permeability of the host rocks increases significantly when the mine face approaches the tectonic disturbance. The flow rate of water reaches critical values. The use of roof bolting restrains the unloading of the boundary rocks from the rock pressure and keeps them in a triaxially compressed stress state. The permeability value decreases by the value of its technological component. In different areas of the intersection of tectonic disturbance, the water inflow into the mine working with roof bolting is 3-8 times less than in the working, supported by frame supports. Therefore, the use of roof bolting allows not only to keep the mine working in a stable state, but also to significantly reduce water inflows at complicated hydrogeological conditions.

GEODYNAMICS

Purpose. The purpose of the paper is the reconstruction of the geodynamic development of the shear dislocation zone (shear stress fields) of the Krasnoarmiiska monocline (KM) of Donbas (Eastern Ukraine) and determining the relationships of their impact on the emergence of gas-dynamic phenomena (GDP) in coal sediments. Methodology. Methods of digital geological cartography, mining-geometric simulation, geological-structural analysis, and structural-geomorphological reconstruction are used for the analysis of structural-geological information. A complex of methods for statistical processing of data on the tectonic disturbance is used – estimation of the frequency of azimuth orientations by the roses-diagram method. Techniques of morphotectonic analysis of the coal bed (a mathematical technique for identifying the gradient structures) are applied. Results. A tectonic model of formation of pull-aparts in the mode of transtension on the territory of KM (on the example of “Dobropilska” mine) is proposed, which results in manifestations of GDP (in particular “wet blowers”) in the form of a small kettle of subsidence in zones of en echelon overlapping of shears. The latter ones are formed under the action of the shear field of tectonic stresses (the axis of space shortening is (σ1) due to the horizontal shear is oriented in azimuth 160-170° (340-350°), the axis of elongation is (σ3) – 70-80° (250-260°). At this, the combination of fringing Y and T faultings in the conditions of transtension, most likely, provides gas permeability and water permeability of the zone. Structure-kinematic relationships of formation and development of shear dislocations of KM at Donbas are researched. Originality. The structural-kinematic relationships in the formation and development of shear dislocations of the Krasnoarmiiskyi district of Donbas and their impact on the formation of GDP zones were studied firstly. They based on the developed digital model of the actual tectonic disturbance of the rock massif on the example of the mining allotments group of KM. It is established for the first time: a) subparallel disjunctives of the NE orientation (15-30°), regardless of morphology, are as the boundaries of parallelogram-like blocks, forming either scaly packets or packets of fault scarps (depending on the morphology of the faultings), limited in the strike by the fault planes of N-NE and SW fall; in the case of scaly packets in the orientation of the fall of the fault plane it is dominated by the E-SE direction, the faultings limiting the fault scarps are characterized by the opposite WN direction of the fall; b) faultings of SE orientation are morphologically represented by shear-thrusts, and with depth change not only the angle of incidence from 35° to 85°, but also the azimuth of strike (from 20-25° to 50°), forming a fanlike feathering of the main faulting in the plan; c) faultings of different morphology are represented not by a single fault plane, but by a series of disturbances on all stratigraphic horizons, which form a zone of faulting formation – a vertical "tectonic strip"; d) in the SE part of the mine "Pioner" a duplex of compression (transpression mode) was found, it is expressed by a folded system (F), up to 287 m wide and fragments of sloping, changing the strike of the Novoiverskyi thrusts; e) the zone of tension duplexes located in the chain, which have a characteristic broken-step configuration at the "Dobropilska" mine, to which “wet blowers” are connected with, develops due to local strike (transtension); f) paragenesis of deformations in the study area corresponds to the shear field of tectonic stresses with north-northwest direction of compression and east-northeast tension, in which fault-shear displacement occurs along with the disjunctive breaks. Practical significance. The established relationships of the impact of shear tectonics on the formation of GDP in coal beds are important both by clarifying the mechanism of tectonogenesis and the nature of pull-aparts formation (en echelon zones of tension), and by the possibility of using additional prognostic criteria for searching for accumulations of free methane and its sudden manifestations (GDP) in coal beds. The application of knowledge of these relationships at mining enterprises will allow reducing the costs for the struggle against dangerous GDP manifestations and predicting them reliably.

Specific Features of Mapping Large Discontinuous Faults by the Method of Electromagnetic Emission

In this paper, the authors consider the issue of processing the data of electromagnetic pulses (EMPs) recorded in mine workings and their interpretation. The Sami fault (Russia, the Murmansk region) was chosen as the object of the research. A number of experiments, including measuring the EMP level along the fault and the analysis of the results, were performed by the authors. The paper also presents a previously unconsidered method of transition from geological concepts to electro-technical ones, the aim of which is to identify the dependences of the amplitude of electromagnetic field anomalies on the parameters of active tectonic disturbances. The authors assumed the dependence of the amplitude of anomalies on the geological parameters of the rock mass and the thickness of the tectonic disturbance.

Study of the technogenesis of the Degtyarsky mine by audio-magnetotelluric express sounding

The audio-magnetotelluric express sounding was performed at four sections crossing the mine field of the currently not functioning Degtyarsky mine. Field measurements were carried out by a universal broadband receiver “OMAR-2m” with active electromagnetic field sensors developed at the Institute of Geophysics UB RAS. Based on the obtained data, deep sections of the electrophysical parameters of the medium – apparent resistivity and effective longitudinal conductivity – are drawn. The nature of the geoelectric structure of the section allows mapping of the major lithochemical contamination plume and identifying the tectonic disturbance zones that drain aggressive mine waters. The mine waters of the Degtyarsky mine are a source of dangerous technogenic pollution. Despite the neutralization of surface runoff, underground routes of acidic water migration occur along tectonic cracks, primarily in the zone of the regional Serovsko-Mauksky fault. Tectonic zones in the mine area contain contaminated fissure-vein water, which is transited at a depth of 70 to over 200 m. Discharging ascending springs of such waters can be located at a great distance from controlled hydrological objects and pollute sources of drinking and household water supply. Urban development in the western and eastern parts of Degtyarsk does not fall within the distribution zone of polluted water. The southern part of the city is located beyond the watershed of the mine water flow area, but a danger of local contamination by tectonic disturbance zones remains possible. The worst environmental situation is observed in the northern outskirts of Degtyarsk, which falls into the area of heavy pollution of underground and surface waters. Besides, acidic fumes from the flooded Kolchedanny quarry can affect the health of city residents when emitted to the atmosphere.

Possibility of application of the method of observing the natural impulse electromagnetic field of the earth for allocation of watered faults on the example of Yeristovo quarry

One of the important tasks of operating the Yeristovo iron ore deposit is to reduce the level of water inflows, which complicate its development. The article presents the results of applying the express method of observing the natural impulse electromagnetic field of the Earth to isolate flooded faults in areas adjacent to the Yeristovo quarry. The features of the geological and tectonic structure of the territory of the Yeristovo field are considered. According to the tectonic map of Ukraine, the main deep faults characteristic of Srednepridneprovsky and Ingulsky megablocks of the Ukrainian shield in the area of study sites are highlighted. A method for conducting field studies by observing the natural impulse electromagnetic field of the Earth is presented. The studies were performed using equipment such as a radio wave indicator of the stress-strain state of rocks according to a previously developed technique. According to the results of the field studies, for the first time, maps of the density of the natural impulse electromagnetic field of the Earth flux were constructed for this area, which made it possible to isolate and trace the positions of watering faults. In addition, to visualize the most difficult fragments of the structure of the plots, three-dimensional models were built. Four zones of reduced values of the natural impulse electromagnetic field of the Earth (less than 3 conventional units) were identified on the studied areas. They are characterized by: the western tectonic disturbance - has a width of about 60 m and a strike azimuth of 3-5˚. The tectonic disturbance following it to the east is about 50 m wide and the strike azimuth is also 3-5˚. It is followed by an insignificant tectonic disturbance, which inherits the direction of the Krivyi Rih-Kremenchug break and has a width of about 20 m. In the east of the studied sites, there is a tectonic disturbance with a strike azimuth of 3-5˚, about 20 m wide. Since the azimuths of the strike of the identified tectonic disturbances coincide with the Main and Yeristovo faults characteristic of this territory, the identified faults are their feathering. On the basis of the conducted research, it is possible to recommend the use of water catching wells using a reasonably economical and reliable method of observing the natural impulse electromagnetic field of the Earth. It is advisable to lay them in the zones of minimum values of the natural impulse electromagnetic field of the Earth, within the southern parts of the research sites. The use of advanced observations will avoid unproductive costs when drilling water-reducing wells.

MANAGEMENT AND PREVENTION OF EVENTS THAT CAN CAUSE CATASTROPHES

The dam Mavrovo on the Mavrovo Lake was built on the river Mavrovska at the very exit of the Mavrovo field. The dam can relay in several cases: war, natural disasters (tectonic disturbance, earthquake, flood and human factor), and antiterrorist attack. During the demolition of the dam, a flood wave would be formed along the valley of the Mavrovska River and the Radika River. The basic, main and priority goals that are expected to be achieved after the conducted research, analysis and preparation of this paper are as follows: Realization of the possibilities for reaction and support for cracks, collapse and other damage to dams, Realizing the possibilities for reaction and support if cracks, crashes and other damage to the dams, creating conditions for the occurrence of infectious diseases in humans, animals and plants, achieving the possibilities for reaction and support if cracks, crashes and other damage to dams, resulting in greater material damage to the habitats, destruction of industrial capacities of livestock farms, etc., Realizing the possibilities for reaction and support in the event of an earthquake, Realizing the possibilities for reaction and flood support, Realizing the possibilities for reaction and support during intensive snowfall, snow drifts, avalanches, landslides and more land-slippery landscapes, Realizing the possibilities for reaction and support at extremely high or low temperatures and dense fogs and I have achieved ment opportunities for response and support large-scale fires. In the event that there is a drainage of the dam, if there are no previous optional solutions for managing the possible consequences, there will be a natural disaster on a considerable scale.If the dam is destroyed, it is expected to be destroyed: The entire road infrastructure from Mavrovo to Debar; The economic capacities of the same move, Family homes after the flow of the river radika. There are climatic and pedological consequences and Disruption of biodiversity in the region.