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Abstract

Ñontent

Introduction

Topicality

The coal industry of Ukraine is gaining more weight in the energy security of the state. The competitiveness of coal mines is provided primarily by improving the efficiency of coal production and increase the load on the stope. However, this task is much more complicated because of restrictions on gas–oil ratio, which has been steadily worsen with increasing depth of development and increased gas content of coal deposits.

Among the most effective technologies for reducing the gas content of rock mass has a special place degassing of coal seams and their satellites underground degasification wells drilled from the expression botok supported behind the lava. In the process of revitalizing the undermining of displacement thickness trunks degasification wells intensely deformed and destroyed, especially in the vicinity of development working and degassing efficiency drops sharply. In this regard, improving the parameters of underground degasification wells operated behind the existing lava is relevant for the coal industry of Ukraine task.

Goal

Improving the efficiency of degassing by improving the parameters of underground degasification wells operated behind the current working face.

Research tasks

Determine the conditions of the deformation of the degassing wells in the vicinity, intensely deformed development working

The object of study

The process of deformation degasification wells.

The subject was

Degassing boreholes.

Research methods

The paper will be used in the computer simulation of a mountain range, and the results of experimental studies in mines.

Scientific positions

Establishing bundles that increase the permeability of the array around a wellhead exponentially on approaching the circuit output and reduce the effectiveness of the wells due to increased air leaks through the mouth, slices, the value of which is a logarithmic function of the displacement of the roof and which reduces production efficiency of the wellbore.

The practical significance

Will be developed and improved measures and means to reduce the strain degasification wells and method of determining the degree of deformation of the wellbore at a shift of rocks.

1. Survey information

1.1. A review of research on the topic in the Donetsk National Technical University

Institute of Mining and Geology, Donetsk National Technical University is one of the leading scientific organizations, which is responsible for improving the parameters of underground degasification wells.

1.2. A review of research on the topic in Ukraine

In Ukraine, the research parameters of underground degasification wells Surveying Department is engaged in Dnipropetrovsk National Mining University.

1.3. A review of research on the topic in the world

    Degassing issues involved in many institutions of the Russian Federation:
  1. St. Petersburg State Mining Institute named after GV Plekhanov;
  2. South–Russian State Technical University (Novocherkassk Polytechnic Institute);
  3. Moscow State Mining University.

2. The main content of

In a market economy, getting the high profitability of coal mines comes out on top. Ensuring the profitability of coal production can only be achieved by increasing the load on the stope. However, intensification of coal will inevitably lead to an increase in the intensity of gas release into the workspace current stope, which increases the probability of an explosion of gas–air mixture. The capacity of the dilution gas mixture to a safe level by conventional means of ventilation has long been exhausted. That's why the last decade focusing on the improvement of drainage systems.

Despite significant progress in this area degassing efficiency is not always sufficient for the safe management of sewage treatment works, as evidenced by the ongoing major accidents in coal mines in Ukraine and the CIS, which are due to explosions of gas–air mixture. Characteristically, such failures occur approximately with the same frequency regardless of what circuit ventilation applied. Substantial reserve of raising the efficiency of degassing is kaptirovanie gas from uncontrolled development workings, which are adjacent to existing stope [2]. The fact that almost all circuits degassing maximum amount of free gas accumulates Generates space serving lava from previous exhaust portion.

Typically, the vent openings, adjacent to said portion already exist degassing system. In this regard, highly desirable to use these systems for additional capture and removal of methane from uncontrolled excavation workings, which portions are insulated and effectively over 50–300 m or more, still have a residual section of about 2–5 m2. Such a section is sufficient to maintain the integrity of the gas drainage pipeline. In this regard, it is useful to place the pipe in such a place of uncontrolled section of development, which will disappear in the last turn. In this case, it is possible to catch and divert an additional 30–40% of the explosive gas and thereby increase the security of wastewater treatment works. Thus, the study of the distribution of life "living" section of development on the area of its initial section is relevant To solve this problem, we used a complex method of research, including the physical and mathematical modeling of the forbidden section of the individual strains of advance working, as well as the results of field observations of mine, in which the measured dimensions of the cross section of development and made their photographic images. There were analyzed Vano six mathematical and physical models, 8 and 25 of the Preparatory workings of 6 mines of the Donbass coal mines and several non–CIS countries. We used the results of their own research, as well as the previously published data of other authors. This provided a database, which is built on the basis of a representative sample. Tion analysis of the data sample is given below.

Uncontrolled land development working (mine them. Syadko Over–Red Army and West number 1) falls into several geomechanical zones, which are characterized by different intensity of rock pressure (Fig. 1). To permit comparison of the results of several experiments graphics strain constructed in dimensionless variables cross–sectional area, and the development of cross–sectional area in front of the window of lava is taken as unity. After passing through the window generation portion lava isolated and misses the active displacement zone (section 1), wherein the intensity of the convergence of the loop and the maximum speed is 5 to 50 mm / day or more. Length of the zone of active displays is 1–2 monthly podviganiya lava and depending on the speed of podviganiya ranges of 30–250 m On this site there is an opening of cracks and delamination around the production of species, leading to an intense gas–division. Therefore, preserving the remaining section of the uncontrolled development of land at the site is very important.

At site 2 is damped displacement on the contour generation. Despite the diminishing rate of deformation section of development and its host rocks, gas evolution continues, and within the second area is the possibility of captured between 30 and 100% of the amount of gas that is trapped in the area 1. Within Phase 3 speed shifts the contour of uncontrolled production falls to a minimum. Depending on the state of development of the lava front of the window, the method of its protection and load–carrying capacity.

Changing the residual section of development behind the moving longwall

Fig. 1. Changing the residual section of development behind the moving longwall

In general, the nature of the decay of displacements on the contour plot of uncontrolled production is described by an exponential. In the process of displacement rocks around uncontrolled development working stratify and form a man–made folds in the roof and the soil (Fig. 2). This is typical of the nature of the displacement of a gentle fall. Section uncontrolled production decreases substantially in a vertical direction, although the convergence of the sidewalls also takes place. Typically lateral displacement value is 2–5 times less than convergence of the roof and ground. Sectional shape of the residual uncontrolled production during deformation varies, and in front of the window, it may acquire lava pronounced asymmetry.

However, the asymmetry value decreases with the decrease of the residual section. In those cases where asymmetry of the cross section is expressed, its value decreases exponentially and varies from 56% to 15% at the end of the life cycle of an uncontrolled output. Fig. 3 is a graph of residual asymmetry smoothing section, expressed as the imbalance of the left and right sections in percentage. We see that at the end of the life cycle of a non–controlled section of advance working–section asymmetry becomes smaller measurement error that does not exceed 15%.

On the basis of the right and left sides of the cross–sections are used separately to use statistical sampling. Fig. 2 shows the experimental data [3], confirming the validity of this approach. The pictures can be seen that with the decrease of the residual cross–section area of uncontrolled production of up to 3–4 m of its asymmetry becomes negligible. However, this value area.

Changing the cross section asymmetry uncontrolled production area with the removal of lava

Fig. 2. Changing the cross section asymmetry uncontrolled production area with the removal of lava

To determine the probability distribution pipeline conservation degassing area uncontrolled generation section has been used the following method. The method described above was provided by a representative amount of data to process the results.

To be able to combine the results obtained by different methods (physical, mathematical modeling and physical experiments), the sizes of all sections have been normalized. This uncontrolled sectional height and width of the developing unit taken and the coordinates of contour points determined in the cross section ranging from 0 to 1. To quantify the cross–sectional areas used point scoring. The initial section of development taken its section opposite the window of lava. Sectional areas, which disappeared in the first geomechanical zone (ie, in the zone of active displacements behind the existing lava – see Fig. 1) assessment administered within 33 balls.

Areas of uncontrolled cross–section, which disappeared within a second of the geomechanical zone administered assessment in the range of 33 to 66 balls. Teaching who disappeared in the third zone, estimated in the range of 67 to 100 ba–fishing. In this section of land, which showed the highest long–govechnost a score of 100 balls. Since the original section was divided into sections with 0.1 original width or height of the cross section, after processing the input data of the above–mentioned method of education of about 300 elk area data uncontrolled section of development. In this case, the data sets are saved in the "coordinates x, y, and evaluation in points." These sets were processed kriging method in the package SURFER, which allows variogram analysis. This ensured is well defined averaging raw data and increased the reliability of the results of their treatment.

All data were reduced to standard conditions under which so forth ABILITY roof rocks and soil produce the same. Thereby providing comparability of results of processing all the data source selection ki, reduction which is implemented using industry methods for the calculation of the displacement on the contour of development workings. [4]

Fig. 3 shows the distribution of point scoring areas of uncontrolled cross–section. These estimates can be interpreted in terms of the probability of saving sectional area of uncontrolled output. The larger point scoring area, the more likely it is recorded. The resulting distribution is consistent with the geomechanics rock displacement on the contour generation. Since the least durable sectional areas which are arranged from the soil. These sites are disappearing due to soil heaving rocks. A low probability of survival are also sections section adjacent to the top of the development and its side walls. Maximum durability have uncontrolled land sections, which are located on a vertical distance from the ground of 0.5 – 0.7 IHS generation section on anti–offset window of lava and the vertical axis of symmetry in sectional half–width of said sections 0.1–0.4 .

Fig. 3. Probability distribution of pipeline gas drainage pipeline conservation on the cross section of an uncontrolled production

Based on these results to analyze the existing layout of degassing or gas suction pipe in uncontrolled excavations (Fig. 4). The numeral 1 indicates the location of gas suction, which is practiced by uncontrolled drainage area of excavation workings. In this case, the pipe is attached appendix A B, which is often referred to as a candle. Scion is required for methane capture at the crest of the uncontrolled production because methane is lighter than air and ska plivaetsya at the top of the section. From a comparison of figures 5 and 6, it is clear that the probability of survival of such a pipeline is minimal. Already within the first zone of the geomechanical clamping system is followed by scrapping candles and / or pipeline. Likelihood of maintaining such a system threads do not exceed 20–30%. This means that it fails to have first–O tens of meters behind the retreating longwall, and much of the methane–children will not impounded, which reduces the effectiveness of the degassing of the recessed portion of uncontrolled development and increases the likelihood of an explosion at the interface with the airway.

Fig. 4. Possible options for the location of degassing pipe

Often left on the soil pipe output in position 3. The probability of such a pipeline pinched between rocks and soil produce high walls, and the probability of its preservation does not exceed 20%. Slightly higher probability of keeping the pipeline in position 4, when it is attached, are in the front frame support at the side wall of output. However, the probability of preserving such a pipeline does not exceed 35–40%.

From the analysis of the distribution in Fig. 5 it is clear that the maximum probability of survival in the degassing duct, if it is placed at position 5. This gas suction structure is simplified because it does not need the plug. Enough to perforate the pipeline itself. In addition, this solution reduces the aerodynamic resistance of the pipeline.

As the subsidence of roof rock pipeline will go down and eventually take a position in which the probability of its preservation is maximized.

At first glance, this position line may move if it is placed on the ground. However, in the process of heaving rocks of the soil is high probability line sliding into a dangerous position 3, since the swelling occurs in the form of invert. The main disadvantage of position 1, as already mentioned, is the need for attachment of candles.

On the basis of the research proved the rational layout of the degassing pipe, allowing to increase the efficiency of decontamination by maximizing the probability of preserving the integrity of the pipeline and increase its longevity.

References

  1. Bryuhanov AM Investigation and prevention of accidents in coal mines / [A. M. Bryuhanov, VI Berezhinsky, KK Bulgakov and others] under. Society. Ed. AM Bryukhanova. - Charles P. - Donetsk Donbass, 2004.-632 with.
  2. Degasification of coal mines. Requirements for methods and circuits degassing. - Kiev: Ministry of Coal Industry of Ukraine, 2004. - 162
  3. Borzyh AF Maintenance, repair and liquidation of the workings of coal mines / [A. F. Greyhounds, YE Zyukov, SN Knyazhev] - Alchevs'k: Donetsk State Technical University, 2004. - 614.
  4. Ukazaniya the rational arrangement, protection and maintenance of mining workings in the coal mines of the USSR. - [Ed. Fourth, ext.]- L.: VNIMI, 1986. - 222.