Bolting (mining)

In mining and tunneling, bolting is the axial linkage of the route expansion . The bolt serves to secure the individual structures against a shear effect in the longitudinal direction during the expansion of the route.

Basics

Movement in the mountains or shooting work creates shear forces that act lengthways on the route. So that the extension of the line can better absorb these shear forces, it must be stiffened in the longitudinal direction of the shear forces. With this stiffening, the individual structures form a complete structure. This structure is able to better absorb the shear forces. The bolting reduces the free buckling length of the extension, which in turn reduces the load-bearing capacityprevented. In addition, the bolting counteracts the destruction of the extension by tilting the individual structures or buckling in the direction of the route. To meet these requirements, the bolt must have sufficient strength against pressure, tension, kinking and bending. In addition, it must be tight and be as easy to install as possible. Depending on the load, several bolts must be installed at the same height. A good bolting is particularly necessary for flexible expansion. With this type of extension, resilience is only guaranteed if the direction of the load differs only insignificantly from the level of the individual extension. The number and spacing of the bolts are standardized.

bolt

Depending on the requirements, bolts made of wood or bolts made of steel are used.

Wood bolting

For wood bolting, round timbers are used, which are sawn to match the required length. The round timbers usually have a diameter of eight to twelve centimeters. The number of bolts depends on the lateral rock pressure . If strong pressure is to be expected, the bolts are inserted as full bolts without gaps. The wood bolting has the advantage that the individual bolts have a low weight and are inexpensive. The bolts can easily be sawed off to the desired length according to the distance between the individual structures. The strength of the bolts can also be easily adapted to the expansion. However, it is disadvantageous that wooden bolts cannot absorb tensile forces. In addition, they fall out of the extension profile after some time without securing, the reason for this being the drying of the wood. There are various bolt holders to secure the wooden bolts. Certain extensions with a web profile have a welded-in pin lock.

Steel bolting

Pipe bolting for sliding bend removal

For steel bolting, spacer irons made of U, L profile steels or tube profiles are used. The bolts are either rigid, adjustable or articulated. Steel bolts are also able to absorb tensile forces. When dismantling from TH profile, such as the plain bend , bolting from tube profiles have proven to be good. The bolting consists of a distance iron with a length adapted to the construction distance. The distance between the individual structures is also determined by the length of the bolting . For this reason, they are also called spacer bars in some mountain areas . There is a tab on each side of the spacer iron, this is screwed to the spacer iron and is long enough to overlap the extension segment. There is a hook screw with a suitable nut in the bracket . The hook screw is attached so that it engages behind the extension, then the screw is fastened with the nut.

Individual evidence

↑ ^a ^b Bochumer Eisenhütte: Connections (accessed on January 4, 2012; PDF; 1.5 MB).
^ ^A ^b Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .
↑ ^a ^b ^c ^d Ernst-Ulrich Reuther: Textbook of mining science. First volume, 12th edition, VGE Verlag GmbH, Essen 2010, ISBN 978-3-86797-076-1 , p. 374.
↑ ^a ^b ^c ^d ^e ^f Carl Hellmut Fritzsche: Textbook of mining science. Second volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1962.
^ Heinrich Veith: German mountain dictionary with evidence. Published by Wilhelm Gottlieb Korn, Breslau 1871.
↑ 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 .
↑ ^a ^b Patent specification: Tensile and pressure-resistant bolting for pit lining with channel-shaped profile. Document identification DE3535858C2 February 16, 1989 (accessed January 4, 2012).

[Quelle_1-1] Bochumer Eisenhütte: Connections (accessed on January 4, 2012; PDF; 1.5 MB).

[Quelle_2-2] A ^b Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .

[Quelle_7-3] Ernst-Ulrich Reuther: Textbook of mining science. First volume, 12th edition, VGE Verlag GmbH, Essen 2010, ISBN 978-3-86797-076-1 , p. 374.

[Quelle_3-4] ↑ ^a ^b ^c ^d ^e ^f Carl Hellmut Fritzsche: Textbook of mining science. Second volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1962.

[Quelle_4-5] Heinrich Veith: German mountain dictionary with evidence. Published by Wilhelm Gottlieb Korn, Breslau 1871.

[Quelle_6-6] 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 .

[Quelle_5-7] Patent specification: Tensile and pressure-resistant bolting for pit lining with channel-shaped profile. Document identification DE3535858C2 February 16, 1989 (accessed January 4, 2012).