Drillability (rock)

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With drillability is defined in the drilling resistance, according to its kind and size, a rock opposes the penetration of a cutting bit. The ability to drill is of great importance in conventional excavation in mining and tunneling . The first studies of the amount of work involved in rock drilling were carried out by Rziha and Rosiwal towards the end of the 19th century . These investigations have already produced a practical classification of the drillability of rocks.

Basics

Every rock has certain properties that are known as rock behavior. The rock behavior is assessed on the one hand by the active drilling resistance and on the other hand by the passive drilling resistance. The active drilling resistance has an effect due to the abrasiveness of the material to be drilled. The active drilling resistance is decisive for wear. The mechanical penetration resistance is called passive penetration resistance. This resistance counteracts penetration. Since the drillability is a decisive factor for the wear and tear of the drilling equipment and for the advance performance, the knowledge of the respective rock properties is of great importance for the calculation of the construction of a tunnel or a mine .

Factors influencing drillability

The factors that have an influence on drillability can be divided into three areas. These are geological factors, mechanical engineering factors and the respective construction company and work process. Geological factors are primarily the properties of the rock to be worked on. Rock properties such as uniaxial compressive strength, shear strength, uniaxial tensile strength, as well as the content of grindable minerals and the hardness and grain size of the rock-forming minerals play an essential role. The rock hardness has only a subordinate role in assessing the drillability of a mineral. Here, the formation of the mountains in the mountain range is of greater importance. Further parameters that have an influence on the drillability are stratifications , fissures and fault zones . The drilling equipment plays an important role in the machine-technical factors. So it is primarily decisive whether a hammer drill or a rotary drill is used for drilling . Further mechanical factors are the power transmission of the drilling rig to the rock. The feed rate and the speed of the drill play an important role here. Another mechanical factor is the drill bit used. Ultimately, the construction operation and work process is also a factor in the drillability. Human factors such as operation and maintenance of the drilling rigs play a role here.

Assessment of drillability

The drillability of the respective rocks can be determined on the basis of investigations with different test conditions. The drillability of the respective rock must be assessed separately according to the drilling method and drilling task. When assessing the drillability, there are large differences in the individual drilling technology areas. So there is an essential difference whether a drilling is a normal rock drilling, a core drilling or a large hole drilling. Based on the drilling equipment used, the drillability can be divided into several drillability levels. The individual minerals to be drilled have partly the same, but often also different, drillability levels for hammer drilling and rotary drilling.

Individual evidence

  1. a b c d e f Heinrich Otto Buja: Handbook of drilling technology. Volume 1, 1st edition, Verlag Books on Demand, 2012, ISBN 978-3848216871 , pp. 73-75.
  2. a b c d e f g Kurosch Thuro: Drillability with conventional blasting. In: Münchner Geologische Hefte series B: Applied geology. Munich 1998, Issue 1, ISSN  1430-5674 , pp. 1-21
  3. a b c d e H. Tudeshi, Thomas Hardebusch: Direct mineral exploration. In: Hossein H. Tudeshi (Ed.) AMS Online GmbH: Advanced Mining Solutions. 2009, No. 2, pp. 4-22
  4. a b c Oliver Spohn: Optimization of the tunnel widening with ongoing rail traffic. Diplomica Verlag GmbH, Hamburg 2012, ISBN 978-3-8428-6563-1 , pp. 73-75.
  5. a b VEB Kombinat Geological Research and Exploration Halle (Ed.): Classification of the F'Gesteine ​​according to drillability, impact drilling and large-caliber rotary drilling. In: Geological Industry Standard. Berlin 1980.