Table of Contents

                
• Introduction.
• 1. Relevance of the theme
• 2. State of the problem of maintaining preparatory vyrabotak. Means and methods of their protection.
• 3. Experience of severe security installations to maintain preparatory vyrabotak.                 
• 5. Conclusion.
• References
                           

  Introduction.

       analysis of modern tendencies of underground mining of coal seams of Ukraine suggests that with increasing depth of mining operations are becoming more common owsheets excavation sites with maintaining development workings behind stope. However, this involves a challenge ensuring their operational status behind lava in zones of influence treatment works and steady rock pressure, as well as the need to develop effective ways and means to protect the excavation workings, in particular protection methods using ordinary rocks and bounding surfaces.

  1. Relevance of the topic.

       Application protection methods using ordinary rocks and bounding surfaces can significantly reduce labor costs by reducing the volume of mortgaged breed while reducing maintenance costs due to the workings increase the bearing capacity constructed structures.

       A detailed study of modern means of protection can be concluded that the security structure, regardless of its degree of compliance with time begins to work as a stamp, including protection methods using ordinary rock and bounding surfaces. This circumstance requires the development of measures to neutralize this effect on the stability of the winning production, namely the determination of the parameters of security structures, in which the forces arising from the action of the load on the security structure, will not be directed towards the production.

  2. State of the problem of maintaining preparatory vyrabotak. Means and methods of protection.

  Further

       coal mining causes the transition of mining operations at great depths, and this, in turn, leads to a deterioration of stability of development workings.

       Due to the increasing depth of the mine development began to move from pillar to develop a combined system with a conveyor carrying Walker (drift) after the stope. The main reason for this trend - the deterioration of the preparatory and high complexity of maintaining them in an array.

       According to research in the areas of Donbass [1,2] there are certain relationship between stability and development workings number of important factors, chief among which is the level of intensity of the wall rocks. Therefore, the development of new technological solutions to protect and maintain the development workings should primarily be aimed at neutralizing this basic factor, ie to reduce the stress concentration in the surrounding rocks production.

  On the basis of the location

       protection excavation methods are divided into the workings of the workings ways :

       ̶ coal seam on the underside, top or bottom and top ripping ;

       ̶ on rocks at some distance from mineral deposits (field production);

       ̶ in areas of low stress (or underworked in nadrabotannoy thicker, and tumbled on compacted rocks, close to the out space or vprisechku to it).

       Field production held steady on the rocks in the soil reservoir to improve conditions. They are connected with the formation or workings with treatment staple, stingrays, crosscuts. Apply field training stands at slaboustoychivyh host reservoir rocks and with a significant service life [3 ].

       MP Zborschik [4, 5 ] proposed a method to use protection workings based on holding them caving roof. Experience of using the method indicates that it is effective only when a continuous system development.

       In most cases, existing methods of maintaining the workings to keep them in working condition fails, and to serve the next column shall be a new - vprisechku to old [6]. Conducting workings vprisechku to goaf [7-9] is a promising way. This technology development is carried out in a pre- weakened array under rocks immediate collapse consoles and the main roof. The main reasons hindering the application of this method are: the need to change the order of fields and training excavation difficulties in implementing complex hypsometry formation and low efficiency when used in difficult geological conditions.

       holding reservoir openings is most common in comparison with other methods. Location relative to production of coal seam is taken depending on the physico- mechanical properties of the host rocks and the type of lining. Develop adjacent to the working face, it is advisable to conduct a Bomb rocks soil formation, without violating the integrity of the roof rocks. At low power Puig rocks (up to 2m) production with the lower recommended ripping with full notch Puig layer [ 10]. When applying arch support allowed Bomb roof rocks on the value of 0.5-1.0 m Large Bomb possible when hard rock roof.

  

   

       Hard guarding facilities generally applies under the Donbass mines and often show their effectiveness. Therefore, before considering measures to expand the scope of the protection methods should be studied experience of their application.

  On

       Donbass mines flat seams mean power usually develop pillar system drifts maturing after lifting stopes. When this scheme is applied vozvratnotochnaya airing. Reverse the order of mining within the floor or tier is due mainly to the difficulty of maintaining drifts behind the stope. Such traditional mining operations often fails to achieve a high load on the lava due to restrictions on the factor airing. Therefore forced to use once-through ventilation excavation sites. The problem of maintaining and preserving the stability of the workings behind the stope is important not only from the standpoint of their possible re- use, but also to ensure the continuous-flow ventilation.

  3. Experience of severe security installations to maintain preparatory vyrabotak.

  Analyzing ways

       protection workings rigid elements worth noting that they are fairly common, but due to the fact that the rigid structure of work in them like a stamp, the last observed indentation in the underlying rocks and as a consequence, squeezing rock soil cavity development and intense deformation of the roof rocks.

  To ensure sustainability

       rigid structures on weak bedrock must involve changes in their construction, which will ensure a joint work and support in the underlying rock formation the load-bearing structure for creating a sustainable base capable of withstanding the weight of the overhanging rocks and provide operational status of production.

       To form the basis of technology may take some of the approaches adopted in soil mechanics, to ensure the stability of the foundations on soft soils.

       Under the influence of the forces applied to a rigid stamp, under the latter there is tension, which increases with the magnitude Surcharging (Fig. 3.1).

  

  Figure 3.1 Schematic diagrams of the stress changes in the underlying soil from the action of a rigid stamp

       arise under great strain plastic deformation (stress redistribution occurs) as the material in this site will have greater susceptibility. Stress diagram under the stamp starts to change (almost triangular diagrams).

       Zone plastic deformations occur at the extremes of the load (Figure 3.2). Then increase the load P, leaving q-const,- zone of plastic deformation  will develop.

  

  Figure 3.2 Scheme of Education zone of plastic deformation.

       moment arises when loading the further plastic deformation zones merge into a single point. In this state of stress is dominated by lateral displacements of soil particles and forms a continuous sliding surface as a result of the thickness of the soil loses its stability.

       To avoid this, as an option, you must change the stamp. And the most simple - to increase its width or depth of the.

       When the width of the die area increases Surcharging application, and, accordingly, reduced ground pressure. With increasing burial ground bearing capacity increases, and the character of the ground surface deformation will be different (Figure 2.3).

       a) Shallow foundations

  

       b) the average depth of the foundations.

  

       c) Deep foundation

  

       Figure 3.3 - Scheme impact stamp on the subgrade for different values ​​of its inception (a, b, c)

       As for increasing the width of protective structures, this is quite a common event, but limited to the cost of implementation. Depth is still laying in the mountain was not considered a science, and perhaps in certain cases, may be at first sight, its non-technological, is quite effective in terms of stability and security structures of the underlying rocks and economically beneficial.

       Therefore, in this paper we propose to consider the possibility and expediency of laying a hard protective structures relative to the surface of the underlying rocks.

  Output.

       Based on the analysis of the problem formulated for further research.

       Based on ideas about squeezing the underlying security facilities under rocks stamp was offered protection mining technology based on the use of harsh security installations for soft rock conditions the soil, which is based on the pledging of this facility relative to the surface bedrock soil, which ensures their stability

  .

  References

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          4. Баймухаметов С.К., Есмагамбетов Х.Б., Спроге А.О. Совершенствование способа поддержания выемочных выработок за лавой при бесцеликовой технологии отработки пластов в Карагандинском бассейне // Уголь. – 1989. – №12. – С. 14-15.

          5. Терентьев Б.Д., Кушнаренко Г.Л., Хамин И.А. Опыт сохранения выемочных штреков для повторного их использования // Уголь. – 1991. – №9. – С. 3-6.

          6. Фомин Е.В., Шапошников В.И., Цыплаков Б.В. Исследования проявлений горного давления при сохранении выработки для повторного использования // Уголь. – 1993. – №11. – С. 19-22.

          7. Егоров А.П., Середенко М.И., Жаров А.И. Управление горным давлением в сохраняемых для повторного использования выработках // Уголь. – 1993. – №10. – С. 11-14.

          8. Кириенко М.И. Повторное использование выемочных штреков // Уголь Украины. – 1980. – №2. – С. 13.

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