Default (mining)

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The miner describes the lining of the gaps in the line expansion as a delay . The introduction of warpage is not only common in routes , the manhole segments are also provided with warpage in manholes and blind manholes .

Need and use

In underground stretches , an extension is being built to protect against falling stone and coal . The individual structures are usually 0.6 to 0.8 m apart. The space between the buildings must not remain free, but must be lined with suitable materials. The delay is intended to prevent loose rock shells from breaking into the route cavity . The delay prevents further loosening of the mountain range. It is therefore of particular importance for the stability of the mine workings . To connect the entire expansion to the mountainsTo guarantee the delay must be backfilled. This results in a more even distribution of the rock pressure around the circumference of the route.

Warping materials

Wooden delay

Wood , steel or molded parts made of lightweight concrete are used as warping materials.

Wood warping

The wood warping is mainly used in building wooden door frames . The gaps are covered with draft wood, also called warping wood, dumping wood or filler wood. As late wood round cut piles are slabs or edge boards used. In floating mountains, planed and jointed posts or planks are used as warpage. This type of warping was also called cladding and was often limited to the roof , where it was necessary, the joints were also warped . A form of wood warping, which was also used in the 20th century for arch construction, is the wooden billet warping. Here, short round timber made of softwood or oak with a diameter of three to ten centimeters are used. The billets are sawn to a length corresponding to the construction distance. In stable mountains, the distance between the billets is 0.3 to 0.4 meters. In the case of steel line expansion, a distinction is made between gap distortion and close-lying distortion. When there is a gap, the wooden sticks are brought in so that they lie next to each other without any gaps. They are alternately placed on the gap between the expansion. In the case of tight expansion, a distinction is made between internal and external distortion. The internal distortion is introduced tightly between the support profiles and also serves as a bolt . The external delay lies behind the expansion. The miner describes the protection of the roofs by means of wood warping as covering or cladding, and protecting the joints as warping. The use of wood warping is only permitted in certain areas in the German coal industry . According to the guidelines for the prevention and fighting of pit fires , the use of wood warping is prohibited in the area of ​​the drives of rubber belt conveyors and in the fire-safe zones of straightening sections and cross cuts.

Warp made of steel

Warping with warping sheets
Warping by means of warping mats

In addition to wood warping, steel warping is also used for steel construction. For this, scrap metal parts , such as used pit rails , are used. But steel sleepers, discarded hoisting ropes and flat-rolled or round steel pipes are also used as warping material. The old materials are shortened to the appropriate size and installed. Correspondingly shaped sheets are also used as warpage. These sheets are three to five millimeters thick and 100 millimeters wide. They are rolled or pressed into a corrugated shape to increase their flexural strength . Further possibilities for the steel warping are warping wire meshes and warping mats. Warp wire mesh consists of two to eight millimeters thick wires connected to form a coarse-meshed network. Warping mats consist of longitudinal and cross bars that are welded together to form a steel grid. There are single warping mats and warping mats that can be rolled up. The draft meshes are available with mesh sizes 100 by 100 mm, 100 by 50 mm and 50x50 mm. Single warping mats have a hook at the ends. To increase the bending stiffness, three longitudinal bars are welded together at the ends. Rollable warping mats are particularly suitable for larger areas, their advantages are ease of transport and flexibility. There are also special backfill mats in which a sealing mat layer made of geotextile is applied to the mesh. With these backfill mats, the sealing mat layer prevents the building material from penetrating.

Concrete warping

In the case of concrete warping, lightweight concrete boards are used that are either provided with or without steel wire reinforcement . The molded parts are either inserted between the extension profiles or placed behind the extensions. There are warping plates made of pumice concrete and warping plates made of prestressed concrete. Warping plates made from pumice concrete consist of blast furnace slag and are reinforced with a steel mesh. Due to this construction, warping panels made of pumice concrete have a high degree of elasticity. Warp plates made of prestressed concrete have pre-stressed wires inside. Due to these wires, these plates have a high flexural strength. Concrete warping is insensitive to rot and corrosion. The panels have good thermal insulation and low weather resistance . However, if the breaking load is exceeded, the panels become unusable.

Individual evidence

  1. ^ A b c Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .
  2. ↑ a b c d e f g Carl Hellmut Fritzsche: Textbook of mining science. Second volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1962.
  3. ^ Ernst-Ulrich Reuther: Textbook of mining science. First volume, 12th edition, VGE Verlag GmbH, Essen 2010, ISBN 978-3-86797-076-1 , pp. 374-375.
  4. ↑ Door frame guidelines of the Arnsberg district government (from July 20, 2001, accessed on January 2, 2012).
  5. ↑ Alexander H. Schneider: Security against collapse in underground mining. ETH dissertation No. 14556, Institute for Geotechnics, vdf Hochschulverlag AG at ETH Zurich, Zurich 2002, ISBN 3-7281-2872-4 .
  6. ^ Gustav Köhler: Textbook of mining science. 2nd edition, published by Wilhelm Engelmann, Leipzig 1887.
  7. ^ A b Heinrich Veith: German mountain dictionary with evidence. Published by Wilhelm Gottlieb Korn, Breslau 1871
  8. ↑ Nieß: route safety and relief slashing in pressurized seams. In: Glückauf, Berg- und Hüttenmännische magazine. Association for Mining Interests in the Upper Mining District Dortmund (Ed.), No. 27, Volume 45, July 3, 1909, pp. 953–959.
  9. ^ Gustav Köhler: Textbook of mining science. 6th edition, published by Wilhelm Engelmann, Leipzig 1903.
  10. ↑ a b Metall Holding GmbH: Rollable warping mat. Company publication.
  11. ↑ Metall Holding GmbH: Welded warping mat with hooks . Company publication.
  12. ↑ Patent specification: Warp mat for pit construction. Application number DE19752550362 19751110.
  13. ↑ European patent application: backfill mat. Online (accessed April 20, 2015).