A driller is using a Shelby Tube Sampler to obtain an undisturbed sample of a so

Question

A driller is using a Shelby Tube Sampler to obtain an undisturbed sample of a soft clay layer encountered 15 feet below the ground surface. The drill operator advances the auger to the top of the test depth specified by the Geotechnical Engineer, and then pushes the tube at a slow, constant rate into the ground. The operator waits one minute, and then at a slow, constant rate, extracts the tube. Once out of the ground, the driller inspects the tube and notices that one end of the tube is obstructed by vegetation that must be cleared to properly see the recovery of soil in the tube. The operator gently taps the tube against the auger to clear the vegetation, sees that there is good recovery, seals both ends of the tube with plastic caps and duct tape to protect against moisture loss, logs the test location and depth, then puts the tube in a carrying rack for transport. As the geotechnical engineer on site, you observed the procedure described above. Which of the following best describes your next course of action? Explain your answer.

A. Double check to be sure tube is clearly marked, properly sealed, and secure in transport rack.

B. Mark the tube described above with an asterisk then note in the drilling log that vegetation was cleared from the tip of the tube before it was sealed.

C. Mark tube described above with the term “void” and request drillers push a new tube at the same depth near the original bore hole.

Explanation / Answer

Answer-

A. Double check to be sure tube is clearly marked, properly sealed, and secure in transport rack.

A suitable filler shall be added to the
void at the top of the Shelby Tube to prevent movement of the sample within the tube. Both ends shall
be covered with plastic caps, then tape should be applied in such a manner as to seal the open bolt
holes and the lip of the cap. Samples shall be kept in a vertical position with the top up during
transporting and storage. Samples shall not be jarred or shaken, and shall always be protected from
temperature extremes, especially freezing. Each tube shall be properly tagged inside and out with all
the pertinent information; project and designation number, road, boring, station and offset, line,
depths, recovery percentage and date. It shall be delivered promptly to the laboratory for testing

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