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Abstract

The efficient protection (support reinforcement) of a wall and heading crossing ensures continuity of the production cycle, and that is a quick moving of the scraper conveyor to the wall. Using low or high bolting as a support reinforcement element in wall and heading crossings allows for the elimination of traditional methods of maintaining longwall-gate crossings, and therefore allows for the efficient use high performance modern wall complexes. The paper presents the long underground experience, of the Knurów–Szczygłowice mine of efficient support wall and heading crossing maintenance, which was bolted to the rock mass with the usage of two pairs of bolts, showing full technical and economical usefulness of this support reinforcement method. The article also highlights work safety and the increasingly common usage of endoscopies when specifying the range of crack areas which directly effects the proper choice in number, load-capacity and length of the used bolts. The underground studies the measurements of the reach of the zones of fracturing and roof stratification (using endoscopes and wire type stratification meters) and the laboratory tests (using the test stand) have allowed to determine the safety factor for maintenance of the longwall gangway crossing, directly resulting in the necessity to install additional reinforcement. The value of the safety factor Sbsc-ch greater than 1 is advantageous and safe, and the value less than or equal to 1 can lead to a significant deterioration of the conditions of maintenance of a wall and heading crossing which was bolted.

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Authors and Affiliations

Stanisław Duży
Piotr Głuch
Grzegorz Michalik
Adam Ratajczak
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Abstract

Neotectonic structures of the Upper Silesia that originated during the last 5 Ma (Pliocene and Quaternary) overlap Miocene grabens and horsts of the Carpathian Foredeep. They had been reactivated in Pliocene as an effect of the young Alpine uplift of the Carpathian Foredeep. It is postulated that ice-sheet derived compaction of a thick Miocene deposits was the most significant agent of the development of neotectonic depressions. Glacioisostasy of mobile bedrock structures was presumably also an important component of vertical movements. The amplitude of neotectonic movements is estimated to 40-100 m, basing on DEM map analysis, analysis of sub-Quaternary structural maps, and the Pleistocene cover thickness. The present-day tectonic phenomena are generated by mining-induced seismicity. These are connected with stress relaxation in the deep bedrock thrust zones of the Upper Silesian Coal Basin.
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Authors and Affiliations

Józef Lewandowski

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