GAA Slope Monitoring System Instruction Manual
Geo-Acoustic Aware (GAA) is a low-cost, reliable solution for the spatial infill of ground movement data instead of traditional instrumentation (Inclinometers, ShapeArray) at shallow depths, and to allow for early warning of movement.
Geo-Acoustic Aware (GAA) is a low-cost, reliable solution for the spatial infill of ground movement data instead of traditional instrumentation (Inclinometers, ShapeArray) at shallow depths, and to allow for early warning of movement. It is used in conjunction with Inclinometers, In-Place Inclinometers, ShapeArray (SAA), piezometers, weather sensors, and other instruments to monitor slow to moderate slope movement rates in landslides, roads and highways, pipelines and tailings dams.
The sensor is attached to a steel pipe (waveguide) in a borehole backfilled with packed angular gravel. The GAA sensor detects acoustic emission stress waves generated by inter-particle friction. Increases in acoustic emission stress waves indicate accelerating slope movement. The sensor is connected to the GAA2820 Data Logger for real-time monitoring.
Acoustic emission stress waves are counted by the data logger during the reading interval (1 hour recommended) and the recorded value is the sum of the waves during this period. This recorded value is called Ring Down Count (RDC). RDC/hour is correlated to the landslide velocity scale presented by Cruden & Varnes (1996)*. The RDC represents an approximation of movement velocity and order of magnitude changes in RDC represents acceleration of the ground.
GAA boasts increased range over other solutions. In cases of large-displacement where traditional instrumentation will exceed their range, GAA can measure, record and transmit data as the waveguide continues to deform in the ground (>500 mm displacement).
The waveguide and data logger are simple to install. The data logger setup and future data collection is done using a laptop. RST’s DT Logger Host Software is also included.
Wireless communication via the RSTAR network allows the data to be combined with other data sets and boasts a large open country Hub-to-Node range.
|Reporting Units||Ring Down Count (RDC)|
|Memory Records||Up to 600,000 records including time, RDC|
|Power Source||Lithium ‘D’ cell battery|
|Battery Life||Up to 1.5 years (assuming 1 hour reading frequency) / 4 memory fills depending on temperature and use|
|Communication||RSTAR, USB (for setup)|
|Dimensions||190 x 75 x 55 mm (7.48 x. 2.95 x 2.17 in.)|
|Temperature Range||-40°C to 60°C (-40° to 140°F)|
|Enclosure||NEMA 4X (IP65)|
|Data Transfer||2,300 data points per second|
|Interval Mode||1 hour recommended (optional 15 minutes)|
|Time Format||Month / day / year Hour / minute / second|
|Memory Full Behaviour||“Wrap around” or “fill & stop” option|
The GAA Slope Monitoring System is commonly used for spatial infill of data from traditional instruments in landslides, roads and highways, pipelines and tailings dams.
View illustrations on how the GAA Slope Monitoring System is used for:
|GAA Surface Assembly (includes sensor and mount, data logger, antenna and secondary enclosure)||GAA2820|
|Waveguide (3 m length, and threaded)||GAA150410|
I’m very happy with the quality of the instrumentation and technical support from RST, as always. They worked with us from the initial stages of the project to ensure that we were fully prepared and equipped to use the RSTAR network for the first time. They delivered everything within the tight project time frame to ensure that there were no delays on site, and the submersible tilt meters looked like new even after over twelve months of being submerged in Thames water!
-Richard Lipscombe, BEng (Hons), Director & Principle Consultant - RL Geotechnical Ltd