Borehole strainmeter

摘要

A recoverable, multiple position borehole strainmeter is provided. The strainmeter includes at least two anchors having pistons for releasably engaging the borehole whereby to mount the strainmeter in the borehole. A pneumatic actuator for controllably, independently actuating the pistons to engage the borehole is provided. A biasing mechanism prevents the pistons from engaging the borehole when the pistons are not being actuated by the actuator, and a relative displacement sensor senses changes in relative displacement between adjacent anchors whereby to monitor relative mass displacement axially along the borehole between the anchors.