Change in the Rock Pressure when Mining a Coal Seam with a Longwall Face


Annotation:

Development of the geomechanical processes is of great importance for human activity in the underground conditions.  Coal mining is accompanied by displacement of the enclosing rocks, which requires a special approach to study of the geomechanical processes. In particular, this is due to an increase in the productivity of the excavation sections. Increase in the volume of the second working, the length of the longwalls and the size of the extraction pillars will transform all the geomechanical processes occurring in the face. 
Modern coal mining technologies are associated with certain specific features of the displacement of enclosing rocks, which necessitate the development of new approaches to the study of the geomechanical processes. The intensification of work inevitably leads to a change in the geomechanical environment in the vicinity of the face. The article discusses the methods and means of studying the process of rocks displacement as a result of construction of the mine workings. For example, a site is selected at the mine named after S.M. Kirov, long-face No. 24-62. Depth to the developed seam is from 476 to 520 m from the installation chamber.  Average thickness of the seam is 2.5 m, length of the face is 300 m, length of the pillar is 2500 m. The average rate of advance is 10 m / day. 
Based on the monitoring of the rock pressure indicators on the mechanized support section, the wave-like nature of the rock pressure distribution in a long-face during mining of the extraction pillar was determined. The surface of the pressure domes was rebuilt using the Surfer software product, which allowed to track the processes in the face part of the longwall. Data on the pressure in the roof supports were used. In the calculations, the average rock density was assumed to be 2.5 m3/t. Since the surface of the pressure vaults makes it possible to judge the processes in the bottomhole of the mined seam, the height of the random collapse zone is determined from the pressure readings in the support struts. It is the one which presses on the powered support. Repetitive areas of the increased rock pressure were noted approximately every 200–250 m.
Profiles of the surface of pressure arches along the length and in the long-face building cross are given. Considering the processes of structuring the rock mass, an algorithm for finding the height of the pressure arch was developed, which ensures a satisfactory convergence with the actual data.

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DOI: 10.24000/0409-2961-2021-5-65-69
Year: 2021
Issue num: May
Authors:
  • Shinkevich M.V.
    Shinkevich M.V.
    Cand. Sci. (Eng.), Senior Research Assistant, gas_coal@icc.kemcs.ru Federal Research Centre of Coal and Coal Chemistry of SO RAN, Kemerovo, Russia
  • Rodin R.I.
    Rodin R.I.
    Research Associate Federal Research Centre of Coal and Coal Chemistry of SO RAN, Kemerovo, Russia