Safety pillar
In mining, a safety pillar (rarely: safety festivals ) is an area in which no dismantling is allowed to protect various objects . A safety pillar is established by the mining authorities and may not be dismantled or explored without their approval .
Classification
Depending on the property to be protected, the security pillars are divided as follows:
- Medullary security pillars,
- Overburden safety pillars,
- Shaft safety pillars,
- Structural safety pillars,
- Safety pillars for certain underground facilities.
Medullary security pillars
They run parallel to the medullary sheath and have a certain thickness (in the Ruhr area often 20 meters on both sides of the medullary sheath). If several mines are to be built on a deposit , the mine divide safety pillars should prevent water and gas from entering. Due to the development towards composite mines, the safety pillars have lost their importance in recent years. If two neighboring mines consolidated , the Markscheide safety pillar could then be dismantled. A special feature are security pillars to the state border; here, too, a similarly dimensioned security pillar remains between the mine and mining field border and the state border.
Overburden safety pillars
Overburden safety pillars are vertical safety pillars that are left in place at deposits at shallow depths to protect the pit against ingress of water from the day. A prominent example is the marl safety pillar 20 meters thick, which is mandatory for the northern Ruhr area .
Manhole safety pillars
The well-known safety pillars are probably the shaft safety pillars. In order to protect the shaft tube and the daily facilities from the effects of mining, an area around the shaft tube is declared a shaft safety pier. As a rule, this is circular and has a radius of 50 meters around the center of the shaft. Since z. B. continue subsidence with a certain angle of inclination up to the surface of the day, such an angle of inclination is set for the shaft safety pillar, which is usually 75 °. This creates a cone around the shaft, which becomes larger and larger as it gets deeper.
If the deposit is disturbed or if it dips more than 15 °, the angle of inclination is adapted to these conditions, which can result in an elliptical shape for the cone.
Structural safety pillars
Are there any structures requiring special protection such as B. iron or highways , bridges, towers or listed buildings, a safety pillar can also be set for these. The distance and shape are adapted to the individual case, otherwise a building safety pillar corresponds to the shaft safety pillar.
Underground safety pillars
Main mine structures that are supposed to have a long service life (for example explosives magazines) are often protected by their own safety pillar. These safety pillars are individually determined in their horizontal and vertical dimensions and shape.
Effects
Mining losses occur due to safety pillars , since no mining may be carried out within a safety pillar. That is why mining companies always strive to only have to observe the smallest possible safety pillars. If the marrow and marl security pillars can be influenced little or not at all, an attempt is made to avoid multiple or overlapping security pillars by concentrating the systems to be protected within the security pillar. In the case of a double shaft system, only one safety pillar is required for both shafts, which is larger than the safety pillar of a single shaft, but significantly smaller than two individual safety piers. In this case, the two circles are tangentially connected to each other around the shaft centers, giving the safety pillar an oval shape. The underground facilities already mentioned will, as far as possible, be installed in the shaft safety pier.
In the case of steeply plunging deposits, the shafts are often set up in such a way that the shaft safety pillar falls into the lying area of the deposit, which means that no mining losses occur. In the southern Ruhr area, the shafts were sunk in a seam depression wherever possible in order to minimize mining losses. If the shaft is deepened on a saddle, in the worst case the entire coal supply can lie within the authorized persons in the security pillar.
Safety pillars have a major impact on the surface of the surface, as the greatest strains and compressions occur in the transition area between the mined and unscratched deposits, which are mainly responsible for mining damage . That is why in recent times, following recent research, attempts have been made to “penetrate” sensitive areas, i. That is, to mine the coal under areas to be protected over a wide area and with a uniform, previously calculated rate of breakdown. Although subsidence occurs in the process, the damage to the mountains is less as the extremely damaging strains are minimized.
literature
- Gottfried Schulte, Wilhelm Löhr: Markscheidekunde . for mountain schools and practical use. 2nd improved edition. Springer-Verlag, Berlin 1941, p. 280 .
- Fritz Heise, Fr. Herbst, Carl Hellmut Fritzsche: Mining studies . Textbook of, with special consideration of the coal mining industry. 8th and 9th completely revised edition. 2nd volume. Springer-Verlag, Berlin / Göttingen / Heidelberg 1958, p. 611 .
Individual evidence
- ^ Walter Bischoff et al .: The small mining dictionary . Ed .: Westfälische Berggewerkschaftskasse . 3. Edition. Glückauf GmbH, Essen 1981, ISBN 3-7739-0248-4 , p. 197 .