Tiltmeter Instrumentation for Deep Hole Operation
Semi-annual technical rept. 15 Jun-15 Dec 1971
LITTLE (ARTHUR D) INC CAMBRIDGE MA
Pagination or Media Count:
The first of the deep-hole tiltmeter systems developed under the present contract was completed and is under tests in a shallow borehole in a stable rock formation at Bedford, Massachusetts. The performance of the system was found to be on the whole satisfactory and it continues to be satisfactory after more than 3000 hours of continuous operation in the borehole. Nevertheless, a few unexpected problems were encountered during the tests. A tilt noise caused by thermal convection in the water-filled borehole was found to interfere with recording at low signal levels. Apparent drift of the zero setting was observed when the downhole package was mechanically decoupled from the cable. The present data logging system, when operated at sampling rates slow enough to permit long-term unattended operation lacks the capability of recording randomly occurring events of short duration. Most of the problems have been resolved and modifications will be made in the present and forthcoming units.
- Geology, Geochemistry and Mineralogy
- Test Facilities, Equipment and Methods