A real-time alternative to the traversing probe type of inclinometer, the GeoFlex system is a string of closely spaced MEMS sensors that employs a chain of sensors and does not require an on-site operator. It is ideal for data logging and real-time, remote monitoring for critical applications such as construction control.
Typical applications include:
- Monitoring landslide areas above dams, highways, and railroads to provide early warning of slope failure.
- Monitoring ground movements induced by tunnel construction and excavation.
- Monitoring deformations of embankments and retaining walls.
- Monitoring deformation of deep foundation elements.
The GeoFlex system consists of a number of sensor nodes in a vertical string installed in either 1.5-inch (38 mm) diameter Schedule 40 PVC or in 2.75-inch (70 mm) inclinometer casing. 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 PVC pipe or ABS inclinometer casing.
The pipe or casing is typically installed in a vertical borehole that passes through a suspected zone of movement. The nodes are spaced at either 0.6 meters or 2 feet and provide a reading resolution similar to a traversing probe. The system spans the zone of movement and when the ground moves, the pipe/casing moves with it, 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 GeoFlex system is connected to a data acquisition system, and readings are transmitted to processing software that can trigger alarms based on displacements or rate of change.
The GeoFlex system is ideal for continuous, unattended monitoring and can deliver readings in near-real time.
Each sensor is supplied with cable so that it can be connected to the sensors above and below, effectively reducing the number of signal cables to just one. This eases installation, simplifies connections to the logger, eliminates the need for multiplexers, and greatly decreases cable costs.
GeoFlex systems have joints capable of bending to 90°, allowing for a compact shipping option. Five segments, each 3 meters (10 feet) long, can be shipped in a carton measuring approximately 64 x 64 x 64 cm (26 x 26 x 26 in) and which weighs less than 22 kilograms (50 pounds). This allows for the system to be shipped via common overnight carrier as well as fit in most standard vehicles.
The GeoFlex system can also be installed with sensorless nodes at the top of the system, allowing the designer to economize by only monitoring the zone of interest and bypassing the upper layers.
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 GeoFlex system is compatible with Campbell Scientific data loggers, including the CR300, CR800, CR1000 and CR6. The system outputs the displacement as engineering units, requiring less computing power and a lighter load on your data acquisition system. The nodes are preloaded with the calibration information, allowing the segments to be installed in any order.
Slope Indicator offers complete monitoring solutions that include data loggers and software such as Atlas Web-Based Monitoring , which can present profile plots and trend plots of inclinometer data just minutes after the readings are obtained.