Abstract: 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.

Abstract: A generally quadrilateral-shaped building panel has a dihedral root portion extending along a major axis which bisects a pair of oppositely disposed corners. The panel has two similar triangular panel portions which extend from the root portion at a nominal dihedral angle to each other when viewed along the major axis. The panel has margin portions extending along each side edge thereof which can be secured to similar margin portions of adjacent panels. Each triangular panel portion has a crowned central portion which is displaced laterally from a nominal plane containing the margin portions of two side edges of the respective triangular panel and the dihedral root portion. The crowned central portion merges smoothly with adjacent margin portions and acts as an arch so that the panel is subjected mostly to compressive forces. This permits the use of fiber reinforced cement composite material as a substitute for common metal sheets, which can tolerate and are usual under tensile forces.