R-4 – Magnetic Probe Extensometer / Settlement

The R-4 is used to manually measure settlement or heave of soils at various depths, allowing the end user to create settlement/heave.

DESCRIPTION

The R-4 consists of a magnetic reed switch mounted on a graduated tape and reel. The switch is activated by magnetic targets installed at different elevations along an access pipe in a borehole or within an embankment or fill.

The R-4 detects the position of the magnetic anchors outside the riser pipe when it is lowered down the access pipe. The probe is suspended by a single graduated tape that incorporates the electrical leads. The tape graduation is used to determine the probe’s precise position relative to the magnets. Comparison of these locations allows heave and settlement determination.

The magnetic anchors are available in three configurations: leaf spring anchor for borehole installation, plate anchor for embankment or fill installation and datum magnet that is fixed directly to the bottom section of access pipe. The leaf spring anchor can be pushed in place or lowered with the access pipe and released with an external draw wire.
The plate magnet is a plate with a central hole. The plate magnets are installed over the riser pipe and between the layers of placed fill, as the filling operation proceeds.

Telescoping couplings are used where deformations exceeding 1% are expected.TheR-4system is compatible with standard inclinometer casings. The use of a probe centralizer is recommended for repeatable readings.