Abstract
- Introduction
- 1. Theme urgency
- 2. Goal and tasks of the research
- 3. A review of research and development
- Findings
- List of sources
Introduction
The major condition of high-efficiency and safe work of mines is providing of the working state of the mining making with minimum expenses on their realization and maintenance.
Providing of the working state of making in the flow of all tenure of their employment becomes more important in connection with passing of mining works to the no-bottoms and in more difficult mining and geological conditions. But for such cases, research works and experience of mines showed that even on no-bottoms it maybe to provide in the difficult mining and geological conditions, as a rule, maintenance-free maintenance of making with a cost and losses of coal cutout in spurns, on condition of correct choice of their location in an array, methods and parameters of guard and facilities of maintenance on the basis of engineer calculations of moving of array, displacements of breeds in making and loading on their.
For this purpose by research institutes, (VNIMI, DonCI and DNTU), methodologies of calculation of displacement of breeds were made in the mining, that allowed to study all factors influencing on displacement breeds in mining and their deformation. Methodologies of calculation are intended for the decision of practical tasks of choice of rational location, method and parameters of guard and facilities of maintenance on-condition in the flow of the set tenure of employment of all unsealing, preparing and joining to the cleansing coalfaces preparatory making on coal.
1. Theme urgency
Mining pressure (m. p.), collective concept in a mining geomechanics, uniting totality of the power fields (tense states) formed in the earthly bowels
of the earth because of natural and productive influences. By the main causative agent of m. p. a gravitation serves; additional causative agents, having
different prevalence, duration and force of action, are geotectonic processes, and also productive activity on getting of minerals, building of underground
and surface building.
Continuously or saltatory redistributed in pedigree arrays by virtue of different reasons, m. p. able to produce both destructive and useful work
(for example, on the facilitation of mining). Phenomena caused m. p. (deformations, displacements and destructions of elements of pedigree arrays and earth
surface, with–operation of elements of arrays with engineering building, including loading of support of the mining making), known in a technique under
the name the displays of mining pressure
, an expedient management presents one of major practical tasks of mining production and mining science that.
A correct location, realization and maintenance of the mining making, is facilities of the effective local adjusting of m. p. that find a wideuse on mines
(for example, for a fight against mining shots due to the passing ahead coulisse of protective
layers). Concept of m. p. there were Studies in 19
century about a management m. p. found a reflection in labours of М. Protodiakonov old, P. Cimbarevich, V.D. Slesarev and row other
soviet researchers. Abroad substantial studies are undertaken К. Bah (Germany), G. Shpackeller (GDR), F. Fenner (Chile) by Pestilence (GERMAN FEDERAL REPUBLIC), А. Labas (Belgium) and other.
For fastening of the preparatory making most distribution was got by metallic arch and circular pliable frame supports. Pliable support is able under the
action of pressure of mining breeds to abbreviate the sizes, and consequently, and crossrunner of making as a result of displacement of elements or their
deformation at maintenance of bearing strength and capacity of construction.
The elements of metallic pliable frames are executed from special, connecting them inter se lapped by means of collars and screw-bolts; pliability of support is
arrived at due to skidding of elements of support in the places of their connection. Mixed frame support consist of the reinforce-concrete hollow
(tubular and rectangular) bars and metallic headtrees, connected through the suspended gib. As an independent type of support, especially in mining industry,
in combination with frame supports use the roof bolting.
Apply (mainly on ore mines) also rigid metallic supports (trapezoid, arched and ring) from flange beams and former in the use rails with connection of elements
protective straps and screw – bolts with nuts, rarer – by means of the special shoes. Timber frames set in making usually in the distance a 0,51 m one from other.
A roof and sides of making between frames are barriered to of inhaling – reinforce-concrete flags, metallic grates and nets of different constructions, boards.
Timber frame support is mainly applied in making of small section and with small tenure of employment (3–5 years). Making with considerable tenure of
employment, as a rule, fastened by noncombustible materials (by a metal, concrete and т. of д.). The frames of trapezoid form set usually through a 0,5–1 m.
with fixing of roof and sides of making between frames wooden inhaling. At pressure from the side of soil of making apply the reserved (complete) frames with
a ledger.
The timber curbing support erected in the preparatory vertical and sloping (over 45°) making of small section (pit-holes, skates, of and other) is continuous,
when crowns are laid one on other, and on bars, when between crowns bars are set long a 0,5–2 m. Crowns make from a roundwood or squared beams and
connect inter se a sealing-off in a paw
, and bars with crowns – usually in a slot.
However the cases of destruction of recommended supports took place, for example, in the zones of tectonic violations on the contacts of geological blocks.
On a the same depth in one cases of deformation showed up as falls and destructions of roof, in other – in destruction and hold – out of ribsides,
troubling of soil.
2. Goal and tasks of the research
The purpose of the master's work is to compare the methods (VNIMI, DonCI and DNTU), with real testimony and determine a more accurate ones.
3. A review of research and development
As a result, numerous experimental and theoretical studies, as well as the practice of mining were identified significant deficiencies with arch arch support: inconsistency compliance (300–500 mm) and the bearing capacity of the lining (150–200 kN) conditions to maintain the workings of high rock pressure and unstable rock walls, lining s proof pressure side rocks, as in relation to the lateral forces has a low resistance; lining can withstand heavy loads and maximum compliance only in circumstances where the direction of the latter coincides with the direction of displacement of rocks; lining unable to restrain processes bundles and caving around production; lining provides only a protective function arch production, reinforcing the not his; Mount workings very laborious and requires high metal consumption; Mr. lining yourself a satisfactory maintenance of workings and arises the need for additional security installations. Increased compliance lining in difficult geological conditions did not remove the above drawbacks, as SVP frames have a low bearing capacity. The destruction of the rock mass increases the load on the arch support. At low load-bearing capacity and lining sufficient compliance, destruction of breeds not only suspended, but has intensified. Resistance drifts supported frame-arch support, with pillar system development and in high rock pressure at great depths, determined by the formation length of development 5 main areas of stress-strain state of rock massif located: outside the influence of the treatment works; 60–70 m in front of the lava; in the range of 0–40 m behind the coalface; in the range of 40–200 m. behind the coalface; more than 200 m. behind the coalface. In this paper, L. Bulat and V. Vinogradov emphasized that throughout the traditional technology used and retaining supporting frame-fixing workings arch support long exhausted its possibilities. This conclusion is based on studies of 60–90 years. Which showed that there is no economically feasible rigid frame supports in excavations carried out in the weak and medium strength rocks at great depths, can not resist the pressure of the mining. so to deal with the formation of the fracture by increasing bearing ability of lining inappropriate.
Pic. 1.Chart of setting of bar of strengthening(animation, 6 shot, duration of 1 with, 5 reiterations, size 85,2 КБ)
Pic. 2. State of making on the investigated mine of а) and б) Tests of lining of KMP–AH3 with the interlocks of ЗШ.000 on the stand of the Donetsk research coal institute(DonCI)
The problem of sustainability of development workings excavation sites is one of the main problems of underground mining of coal seams, without which it is not possible to ensure the safety of mining operations and increase technical and economic efficiency of operation of coal mines. Research and practice of mines show that the cost of fixing and 1 km of development workings in the range of 5 to 9 million USD, modern requirements of cost-effective and safe coal mines in Ukraine on developing flat coal seams 0,85–2 m., best meets conserving technology developments for reuse through the use of effective Anchors, shoring strengthen security and artificial structures, however, the practice of the mines, earning their seams up to 2 meters in difficult geological conditions (large mining depth, the presence of areas of high rock pressure, layered and fractured rocks immediate roof and main roof rocks difficult collapses) supports and roof bolting gain a working load capacity of 50–150 kN/m2 and existing security structures showed their lack of technical and economic efficiency or safety applications. When choosing their parameters in accordance with existing regulations state protected workings is often unsatisfactory. Unsatisfactory condition worsens conditions of ventilation openings excavation sites, reduces mining safety, causing the need to perform them in a laborious and costly repairs, which reduces the load on the face output and ultimately leads to inefficient mines.
Findings
By means of prognostication of deformations of mining, it is possible to define the type of support, for it best stability. On the example of it many enterprises use the exactly that type of support that most befits, at data of mining and geological conditions. In result of undertaken studies possibility compare methodologies of prognostication of the state of the district making appeared, and define all dignities and lacks of each of them.
List of sources
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