Development of a Small Soil Strain Gage
Report Number: AFSWC-TDR-63-3 Author: Truesdale, W. B. Corporate Author: Armour Research Foundation Date of Publication: 1963-03 Pages: 68 Contract: AF29 601 5343 Project: 1080 Task: 108006 AD Number: AD0402706 Original AD Number: AD-402 706Contrails does not possess a copy of this report. Click here to offer Contrails a donation of this report
Abstract: A small strain gage was developed for the measurement of static and dynamic strains when em bedded in soil samples. The gage itself consists of two sets of two coil discs; associated instrumentation includes electronic driving, amplifying, and recording circuitry. One set of coils is embedded in soil as the strain sensing element; the other is externally positioned to serve as a reference. The principle of operation is that of an air core differential transformer with a null balancing system to permit accurate measurements of small strains. The gage is a reliable precision measuring device. Results of static and dynamic evaluations prove that the coils can be consistently placed in soil specimens within the spacing and alignment requirements. Thus, the gage accurately defines the relative position of two points in the soil and accurately measures the change in spacing of these points when the specimen is strained.