Geotech Q & A

[owillis28]

I have a coulple of questions from a study session but don't have the answers. I have what I believe is the correct answer but would like the board's knowledge and wisdom to verify.

Here we go:

1. What kind of drilling equipment should be utilized if a contractor is having trouble advancing a solid-stem auger in gravel and cobble?

A. Coring

B. Cone Penetration

C. Percussion

D. Seismic Refraction

My answer is percussion [C]. I choose this answer based on information found in "Principles of Geotechnical Engineering" B. Das ".......is an alternative method of advancing a borehole, particularly through hard soil and rock"



2. What piece of hand-operated equipment is portable and used to measure in situ undrained shear strength?

A. Aerial Penetrometer

B. Pocket Penetrometer

C. Automated Dynamic Cone Penetrometer

D. Geotechnical CPT truck

My answer is Pocket Penetrometer . I choose this answer by guessing. I could not find a lot of detailed information on penetrometers. I could really use some help in explaining the first three answers.






That's all for tonight. Time to get some sleep. I have a couple more questions that I will post tomorrow.





Thanks in advance.





owillis

 

[Guest]

1. What kind of drilling equipment should be utilized if a contractor is having trouble advancing a solid-stem auger in gravel and cobble?
A. Coring

B. Cone Penetration

C. Percussion

D. Seismic Refraction

The choices provided in A. and B. are obvious throw aways.

I would NOT chose D. Seismic Refraction because while this technology is valid for developing geophysical profiles, it really doesn't have anything to do with 'drilling'.

I would chose C. Percussion. I have witnessed percussion (Rotasonic™) drilling through hard rock media (limestone). It works quite nicely. In fact, I will be out at a site at the end of the month where a few exploratory boreholes will be drilled using Rotasonic™ through interbedded (really transitional zone) cemented dolomite that develops into VERY porous limestone. It is awesome to get continuous, relatively undisturbed cores with minimal loss of drilling fluids (e.g. if you hit a zone of contamination you don't have to worry about sending it to the neighbors property).

:2cents:

JR

 

[Tido]

The choices provided in A. and B. are obvious throw aways.
I would NOT chose D. Seismic Refraction because while this technology is valid for developing geophysical profiles, it really doesn't have anything to do with 'drilling'.

I would chose C. Percussion. I have witnessed percussion (Rotasonic) drilling through hard rock media (limestone). It works quite nicely. In fact, I will be out at a site at the end of the month where a few exploratory boreholes will be drilled using Rotasonic through interbedded (really transitional zone) cemented dolomite that develops into VERY porous limestone. It is awesome to get continuous, relatively undisturbed cores with minimal loss of drilling fluids (e.g. if you hit a zone of contamination you don't have to worry about sending it to the neighbors property).

:2cents:

JR

I agree with JR and for number one Das book says pocket penetrometer. Since I have never used this I cannot explain nicely like JR did.

 

[EL Nica PE]

C. Percussion I have never seen this before, but the next one will be coring but I have only seen this for concrete so therefore C is my answer. Besides Das explains it nicely.

B. Pocket Penetrometer

 

[Guest]

C. Percussion I have never seen this before

When I am at the investigative borehole site where we are using Rotasonic™ (percussion) I will snap some pics for you and post.

JR

 

[Guest]

^^^ It took me a little while to get out there ... but this past week was the week! :woot:

Pictures as promised ....

The Rig-Mount Setup

The Rig-Mast Setup

Close-Up of Vibrating Head

Quality of Collected Cores ....

Oh ... and the mark I left behind at this work site ...

Overall, a very good exploratory characterization! I am quite satisfied with the quality and efficiency the Prosonic™ rigs achieve for environmental characterization projects.

JR