Rotary Drilling
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| Drill Rig |
"Types of rotary drilling include:
- direct rotary drilling;
- reverse circulation rotary drilling;
- dual-wall reverse circulation drilling;
- core drilling."[1]
A rotary drill advances a test hole by rapid mechanical rotation of the drilling bit (e.g., blade, tricone, and coring bits), which is made of carbide, tungsten, case-hardened steel, and diamonds. The bit cuts, chips, and grinds the material at the bottom of the hole into small particles. The cuttings are normally removed by pumping water or drilling fluid from a sump down through the drill rods and bit and up through the annular spacing into a settling pit and back to the sump. Compressed air is also available on many rigs as an alternative to remove the cuttings from the hole. Air rotary drilling is essential for drilling in karst areas where circulation loss is expected.
Rotary-drilling methods can advance test holes in a wide variety of materials, including hard rock. Rotary drilling may be the only practical method of advancing holes and obtaining undisturbed core samples from certain types of soil and rock materials.
Best Practices Resources
National Engineering Handbook: Chapter 5 - Engineering Geology Logging, Sampling, and Testing
Citations:
Revision ID: 4043
Revision Date: 10/25/2022