Volume 35, Issue 3 (May 2012)
Automatic Monitoring of Inserting or Retrieving SPT Sampler in Drillhole
This paper presents a new device for the automatic monitoring and measurement of drill rod and sampler depth associated with conventional standard penetration testing (SPT). The device consists of a depth tip transducer and a data logger. The transducer can be firmly mounted onto the drillhole casing on the ground surface. The data logger monitors the passing of the sampler and rods through the transducer into the drillhole during rod insertion or retrieval and therefore records the tip depth in real time. The paper presents the results of calibrations and laboratory and field trials. The test results demonstrate that the device can accurately, reliably, and automatically measure the vertical displacement, velocity, and acceleration of rod insertion or retrieval in real time.