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Abstract

Content

 

Purpose: investigation of stability of development workings of steep seams at depths of modern design.
idea of work:Is to use the geomechanical features and regularities of formation of the stressed state of the country rocks in the vicinity of excavation to reduce the harmful manifestations of rock pressure in the depths of modern design.

Object of study:Sub– nadrabotanny rock mass.

Subject of study: the processes occurring in ugleporodnom array in the conduct of mining operations which are possible manifestations of natural hazards.

Methods: to achieve this goal they use the following complex: analysis and generalization of experience in the development of shallow layers of the Donbass, the statistical processing of experimental data, taking into account the physical nature of the processes occurring in ugleporodnom array.

Scientific value of the work:is the justification for ways to improve the stability of the conveyor (haulage) drifts depend on the manifestation of a complex of natural hazards in the discharge, including the reality of the destruction of the sedimentary, long time intensive array containing organic matter, gas–saturated aqueous solution having the memory.

Introduction

Development of Coal Industry of Ukraine is associated with periods of growth and decay of large amounts of coal produced. Throughout history, the main supplier of coal has been and remains the Donetsk coal basin. In 1916 in the Donbass coal mined 28.6 million. Then, in connection with the First World War, the October events of 1917 and the Civil War, coal production in 1920 decreased to 4.5 million tons after a period of decline in production growth continued until 1940, where he was equal to 762 million tons, while the performance of trans but working for the extraction of coal amounted to 26.7 tons/month, the ash content of coal 14 %.During the Second World War of 1941–1945. Mines and the coal industry of Ukraine were destroyed.

Restoring them started in 1943 and in 1950 coal output reached 78 million tons, it exceeded the prewar level. In the future, growth in coal production continued to 1976 inclusive, to reach 218.2 million tons the third decline in production continued until 1996, where its volume was only 74.8 million tons of coal ash when it rose to 33,8 %, while labor productivity has decreased to 15.6 t/month. All these figures were much worse compared to the industry in 1940 and 1950. In the crisis period of the entire national economy of Ukraine decline in coal production ceased in 1996, began a gradual increase in 2000–2003. Came the approximate stabilization of production at the level of 80–85 million tonnes per year.

The crisis is complicated by the production of not only the poor funding, and geological conditions, which leads to uvilicheniyu of development workings in disrepair, and as a consequence of increased injury of workers. The most difficult conditions to maintain excavation marked a steep fall in the array where there are areas of intense geological disturbance, and working out a joint suite of contiguous layers is accompanied by the formation of multiple zones of high rock pressure. There was a need for improved methods of preparing haulage horizon in terms of location of preparatory (field) workings.

1. Relevance of the topic

Admittedly, in the Donets Basin the main reserves of coking coal concentrate scarce stamps in the Central Region. The basic amount of longwall faces in coal mines in the area, located on the horizon with a temperature of the rock mass around 36 °C. The It is known [1], the level of injury in areas with high air temperature is 20–30 % higher than in areas with normal micro–climate, and labor productivity by 40–70 % lower. In this regard, the development of steep seams in the area is characterized by a relatively low level of technical – economic indices. This is connected with the geology of the deposit, where coal seams are characterized by considerable fluctuations in output, increased disturbance of the geological and tectonic fracturing of host rocks. It should be noted that the layers are deposited in the suites, the distance between the layers in which 60 % of cases does not exceed 50 m. Therefore, mining operations, one seam is a significant redistribution of rock pressure in the other layers of the suite, resulting in an area of high rock pressure (ZPGD), which has a major impact on the operating condition of mine workings. In the development of coal deposits in the DRC is applied storied way of preparing the mine fields with working off the floors in descending order. The study of displacement and deformation processes of wall rocks showed that when this order is the formation of specific mining areas, and displacement, with an increase in the angle of dip, there is a tendency to shift in rock layers of bedding [2]. This leads to loss of bearing capacity of roof support in the slaughter and abatement goaf, and as a consequence – a possible dip stope and adjacent development workings.

Loss of roadway cross-section

Figure 1 – Loss of roadway cross-section

Because of the specific features of the development of steep seams associated with the angles of incidence greater than the angles of internal friction of rocks under the influence of gravitational forces exfoliating the top of the roof rocks of lava move down, thereby reducing the immediate area of the roof collapsed on the value of nepodbuchennoy of developed space. It has been previously established [3], the smaller the thickness of the rocks close the roof, the greater part of the stope is nepodbuchennoy, and hence the greater the risk of accidents in the abatement face. In reality, the development of steep seams, sedimentary (carboniferous) array represents alternating layers of both coal seams and layers, and a variety of breeds.

A distinctive feature of sedimentary (coal-bearing) of the array is that in all cases, the contact between the clay layers presented differences. In discharge zones argillaceous rocks developing and increasing in volume over time, tear off the layers of stronger rocks.Such processes are occurring in the rocks mezhduplastya, promote, above all, stratification, rock slippage at the contacts under- or nadrabotannyh layers. In such circumstances, represent a serious risk of soil and rock slide that contribute most of the debris drifts.

2. Content work

Most common in the central region of Donbass have such ways of managing rock pressure in the working face, as the retention of the roof on fire, its complete collapse, and gradual lowering of [7]. Drawings are listed below.

Ris. 2

Figure 2 – Distribution of shear stress (N = 1 200 m) in the absence of drifts of funds

Ris. 3

Figure 3 – Distribution of shear stress (N = 1 200 m) above the drifts in the construction of a compliant structure of limited size

Compared to 1970 number of working faces with management holding the roof on fire grew by 19.7 %. This was mainly due to the deterioration of mining and geological conditions, but the method itself has changed significantly. It is known that the collapse of steep seams of the roof, usually starts at the top of the lava, and then distributed randomly, the individual sections along its entire length. To achieve a uniform collapse of rock began to use a special lining to the high load capacity, set by the strike, but the probability of sediment core of the roof has not diminished. Obviously, this is because there are uncontrollable displacement of wall rocks along the normal to the plane of the seam, and that applies lining can not resist.

It is believed that the most promising control method should be classified as a complete collapse of the roof. However, the existing technology of its performance is not different from control by holding the roof on fire. Reduce the spread of ways to manage the complete roof laying out space, which ensures uniformity of rock pressure as the height floors and along the strike of the formation. To expand the scope of the full tab for 16 mines were built RAC crushing and backfill systems (DZK). However, due to the lack of effective means of transportation to the slaughter of backfill material DZK is not exploited. The primary means of mechanization of coal extraction in longwall faces steep seams are hammers [6]. In 1996, with their help, 70 % of the extracted coal. The reasons for constraining the pace of mechanization of securing and managing rock pressure – in the specifics of bed, causing the need for additional specific requirements for means of excavation, as well as insufficient knowledge of the laws of manifestation of the pressure and the interaction of powered supports with side and caved rocks to select promising schemes.

Analysis of results of complex equipment with powered roof supports, designed for faces with a complete collapse of the roof indicates that the specific conditions under consideration can not be expected on a stable reliable operation of the working faces. Given the variety of geological conditions of occurrence of steep seams and experience in the mines, should focus primarily on the full tab out space. Moreover, the technology must take into account the diagonal notch location with the stope hanging over him filling mass that best meets the requirements of the powered supports and testing of seams prone to rash and dangerous to sudden outbursts of coal and gas.

A distinctive feature of sedimentary (coal-bearing) of the array is that in all cases, the contact between the clay layers presented differences. In discharge zones argillaceous rocks developing and increasing in volume over time, tear off the layers of stronger rocks. Such processes are occurring in the rocks mezhduplastya, promote, above all, stratification, rock slippage at the contacts under- or nadrabotannyh layers. In such circumstances, represent a serious risk of soil and rock slide that contribute most of the debris drifts.

On the steep fall of the process of displacement of rock strata earn starts with her bundle. Species are moving in the direction perpendicular to the bedding. The tangential component of the force of weight, promotes detachment of pieces of rock blocks. Fallen rocks roll down to the bottom of lava and rock podbuchivayut roof top of the lava is almost podbuchennoy.

Almost all the drifts are mounted on a steep drop arch support, which has compliance in the vertical direction, and movement of species occurs in a direction perpendicular to bedding (ris.10.3). Therefore, the lock is jammed and the deformation of the lining.

On the steep fall advisable to use a special lining, with compliance, both in vertical and horizontal directions (for example, the Commission's A-4). In addition, different methods of protection and excavation of drifts steep seams.

Conclusions

In the development of steep seams in the DRC should be guided by the traditional method of preparing the mine fields. As a way of formation of extensive workings are useful supple support, located in the goaf. The presence of these supports to prevent settling of rock hanging wall block and sliding rocks of the soil by improving the condition of the wall rocks. This approach in combination with the use of specialized types of powered roof supports, will reduce the likelihood of injury from falls and collapses in the production of repair work on perekrepleniyu drifts. Ensuring the operational status of drifts, thus, increase the efficiency of complex equipment with powered roof supports.

In writing this essay master's work is not yet complete. Final completion: December 2012. The full text of the and materials on the topic can be obtained from the author or his head after that date.

References

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