GEOSTRING – In Place MEMS Inclinometer

Category: Geotechnical & Civil Engineering Instrumentats

EASY INSTALLATION VERTICAL STRING OF MEMS SENSOR NODES LOW COST REAL TIME MONITORING

The GEOSTRING inclinometer is a string of closely spaced MEMS sensors, ideal for real time continuous and unattended monitoring of lateral displacement of soil, rock and structures.

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Description

The GEOSTRING system consists of a number of sensor nodes in a vertical string installed in either 70mm (2.75-inch) diameter inclinometer casing, 85mm (3.3-inch) inclinometer casing or in 38mm (1.5-inch) diameter Schedule 40 PVC pipe.

The pipe or casing provides access for subsurface measurements. The joints between each sensor are robust, allowing the system to maintain a consistent orientation of all the nodes, regardless of whether it is installed in ABS inclinometer casing or PVC pipe.

The pipe or casing is typically installed in a vertical borehole that passes through a suspected zone of movement. The nodes are spaced at 2 ft (imperial version) or 0.5m (metric version) intervals and provide a reading resolution similar to a traversing probe. The system spans the zone of movement occurs, the pipe/casing moves as well, changing the inclination of the nodes inside.

Inclination measurements from the nodes are processed to provide graphs of the casing profile and changes in the profile. Changes indicate displacement (movement).

The system requires casings, GEOSTRING segments, a suspension kit, a bottom plug and a jumper cable.

Nodes, cables, connectors and gage rods are exceptionally durable, making it practical to remove the systems at the end of the project and redeploy them on other projects.

The GEOSTRING system is connected to a SENSLOG data acquisition system, and readings are transmitted to processing software that can trigger alarms based on displacements or rate of change.

A number of Campbell Scientific data loggers can be integrated in a Roctest Senslog for GEOSTRING systems. Two GEOSTRING systems can be connected on a CR6 or a CR1000X. With an MD485 module per GEOSTRING system, the CR1000 can read up to five systems, the CR800 three systems and the CR300 one system.

GEOSTRING systems have joints capable of bending to 90°, allowing for a compact shipping option. Five segments, each 10 feet long (imperial version) or 2.5m long (metric version), can be shipped in a carton measuring approximately 64 x 64 x 64 cm (26 x 26 x 26 in) and which weigths less than 22 kilograms (50 pounds). Because of its compact size, the system can be shipped via standard overnight service.