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Non-destructive Testing of Expansion Bolts
Expansion bolts are used in potash and salt mining to support various sized roof blocks and so prevent them from falling and injuring miners. An important work safety aspect is therefore to check the proper functioning of these support units over the entire service life of a gallery or heading.
In recent years a non-destructive ultrasound test method has been developed for the German coal mining industry for determining the rupture failure of the type of roof bolts installed in the mines.
Based on this ultrasound test system the loads to which expansion bolts are subjected in potash and salt mining can also be determined. Testing includes quantifying the tensile force in the elastic region of the roof bolt as well as determining plastic deformation up to the rupture failure of the bolt.
Further investigations of embedded roof suspension bolts are carried out as part of the Testing of support and stabilising elements.