The typical types of drill rigs are highway, off-road, over-water, and portable drill rigs.
What drill rig is most common?
The most common drill rig is highway.
What drill rig would be best suited for soft, saturated soils?
For soft, saturated soils the best suited drill rig would be portable.
What are the common drilling methods?
The common drilling methods are solid stem continuous flight auger, hollow stem continuous flight auger, mud rotary (rotary wash), and coring.
What method is best for drilling collapsing soil? Why?
The best method for drilling collapsing soils is hollow stem continuous flight auger, because the samples can be taken without removing the auger from the borehole.
What method would be best for shallow holes (<25’) in cohesive soil?
For shallow holes in cohesive soils the best method would be solid stem continuous flight auger.
Explain how soil cuttings are brought to the surface for each method. Which method would be better for large, gravel-sized particles?
For solid stem continuous flight auger and hollow stem continuous flight auger soil cuttings are brought to the surface on the auger flights, for mud rotary – by mud (a mixture of water and bentonite), and for coring – with core barrel. The best method for large, gravel-sized particles would be coring.
Under what circumstances must casing be used?
Casing must be used for mud rotary drilling in cohesionless or highly erodible soils to create a close circulation system.
What method is best for sampling rock?
The best method for sampling rock is coring.
Explain how the standard penetration resistance, or N value, is determined? What is this a measure of?
The standard penetration resistance is determined by counting of blows of the hammer required for three successive 6” penetrations, and the number of blows for second and third penetrations added together. The standard penetration resistance is a measure of compactness and stiffness of soil.
How is a thin-walled Shelby tube sample obtained?
What is the objective of the piston-sampler?
The objective of the piston-sampler is to prevent soil from too fast rising and to prevent soil plugging in the tube.
