The GeoString is a closely spaced MEMS sensor array designed for geotechnical monitoring, tracking ground movement in applications like tunnel construction, embankment settlement, storage tank foundations, and landslide early warning systems.
The GeoString is a closely spaced MEMS sensor array designed for geotechnical monitoring, tracking ground movement in applications like tunnel construction, embankment settlement, storage tank foundations, and landslide early warning systems.
The system can contain up to 200 sensor nodes in a string installed in 85 mm or up to 50 nodes in a 70 mm inclinom¬eter casing.
The casing provides access for subsurface measurements. The joints between sensors are robust, allowing the system to maintain a consistent orientation of all the nodes.
The GeoString is typically installed in a horizontal casing that passes through a suspected zone of movement. The nodes are spaced at 50 cm and provide a reading resolu¬tion similar to a traversing probe. The system spans the zone of movement and when the ground moves, the casing moves with it, changing the inclination of the nodes inside.
Cumulating the deflections along the string produces a graph of the casing profile. Changes indicate settlement or heave.
The GeoString system uses a data acquisition system to transmit readings to a data logger or cloud processing soft¬ware that can trigger alarms based on displacements.
The GeoString system works with many Campbell Scientific data loggers. The CR6 or CR1000Xe can log two GeoString systems per logger directly. The CR350 can log two GeoString strings.
Use the GTecLink data loggers for easy wireless data monitoring. The GeoString Node works with up to 50 GeoString nodes with an external power source or 10 GeoString nodes with internal power.
Process the GeoString data with a spreadsheet or the Sensly web-based monitoring system.
| Sensor type | MEMS (Micro Electro-Mechanical Systems) tilt sensor for inclination readings in two axes. |
| Requirements | Minimum supply voltage of 10 Vdc. Maximum supply voltage of 30 Vdc. Digital RS485 signal requires Campbell Scientific or GTecLink data logger. |
| Weight | 0.426kg per 50cm gauge length. |
| Calibrated Range | ±30 degrees from horizontal over a temperature range of -10°C to +40°C. |
| Resolution | 9 arc seconds or 0.04 mm/m using the CR1000XE data logger. |
| Repeatability | ±82 arc seconds or ±0.4 mm/m. |
| Required Casing | Fits 70 mm or 85 mm outer diameter inclinometer casing. |
| Waterproof | Waterproof to 2 MPa. |
| Jumper Cable | Jumper Cable for connecting the system to the datalogger. |
