Abstract
Inclinometer probes are an industry standard for measuring ground movement; however, this technology has drawbacks, including costly trips for manual measurements, operator error, and limited measurements caused by casing deformation. Relatively new in-place inclinometers based on microelectromechanical systems (M-IPIs) consist of microelectromechanical systems accelerometer segments separated variously by flexible joints or field connection systems and encased in a watertight housing. M-IPIs provide nearly continuous ground movement measurements, accommodate greater ground movement because of their flexibility, and may contain temperature sensors, useful for applications in frozen ground. Two M-IPIs from different manufacturers were evaluated at four research sites in Alaska (a) to monitor creep in frozen ground (vertical installation), (b) to identify and monitor a slide shear zone (vertical installation), (c) to monitor thaw settlement under a newly constructed embankment (horizontal installation), and (d) to identify movement mechanisms within a slide and to evaluate the M-IPIs functionality through large amounts of shear (vertical installation). Each M-IPI was evaluated for ease of installation and subsequent retrieval, durability, and functionality in frozen ground. Measurements from both devices compared well with those from the inclinometer probe; this feature indicated that these devices were suitable for use in cold regions. However, field experience indicates that the installation procedure for each instrument is better undertaken at temperatures above freezing because of the manual dexterity required. For horizontal installations over permafrost, it is recommended that casing ends be secured to posts anchored below the permafrost table and any cold-affected plastic components be replaced between installations to avoid unwanted breakage during reinstallation.