Mar 24, 2021
Matthew Miller and Robert Praeg, members of Measurand’s technical services hosted a technical webinar, “SAAV Extend—Measurand’s latest innovation” on March 11, 2021. They led an expert overview of the newest ShapeArray that features a unique, connectible design that allows clients to increase the total, sensorized length of their instrument, in the field.
Thank you to all who joined to learn more about this new ShapeArray product. Our audience asked several questions that may be of interest to those who work with geotechnical instrumentation.
Can the SAAV Extend be used horizontally?
As you can tell with the top assembly design and construction, this initial launch for SAAV Extend was focused on the mining community for tailings dam raises, but there are efforts for expanding this connectable/extend feature to the other installation methods as well, including horizontally. There is not yet an ETA for this development. The initial focus for SAAV Extend was for the retrofitting of new and existing inclinometer casings and extending that sensorized section of the SAAV Extend in vertical installations.
What is the longest ShapeArray string that we can provide? How does that relate to the SAAV Extend and the total lift segments that can be added?
The maximum number of lift extension segments is a function of the total capable ShapeArray length, which is 200 m, meaning you can add as many lifts as desired up to a maximum total length of 200 m, or 400 x 500 mm segments (including the Base Array).
Can the SAAV Extend be used when the SAAV is installed using a 27-mm ID conduit?
Currently, the SAAV Extend cannot be used in 27-mm ID conduit (1 inch ID PVC). With the space the top assembly occupies, 52 mm ID minimum is needed for the SAAV Extend Top Assembly to fit within the casing. The top assembly includes the cable terminator and the attached springbox assembly. Measurand recommends SAAV for installations in 27-mm ID conduit.
How do we manage the SAAV Extend when extension tubes have been used in an installation?
This would depend on the intention of the installation. If you plan to add a Lift Extension to the SAAV to increase the sensorized length without removing it from its current position, you will want to use the minimum amount of fibreglass extensions as you will need to be able to reach the extension couplers to perform the lift operation from the existing grade elevation. In other words, you need to plan accordingly so that the couplers are within the casing stickup.
If you do not need to perform the lift operation, then you can use additional non-sensorized fibreglass extensions rather than sensorized SAAV Extend Lift Extensions.
Can SAAV Extend monitor multiple zones. Can this be done in a single borehole?
The main requirement is that all sensorized segments need to be continuous based on how we calculate the shape of the instrument. You would not be able to interchange silent segments with sensorized segments. Silent segments can be added to the bottom of the instrument to shift the sensorized section up the casing, or rigid fibreglass extensions from the top of the casing to the top of the SAAV.
What about the logistics of compressing the base ShapeArray installation and adding a new extension. Does the software automatically correct the data to reflect that initial profile before uncompression, essentially marrying those two kinds of before-and-after profiles together?
The cumulative displacement measured by the base array over the monitoring program can be added as an offset to the cumulative displacement measured by the extended array to provide cumulative displacement over the lifetime of the installation. Measurand’s SAAView software will provide an option to apply this offset to SAAV Extend data for each subsequent lift.
Can SAAV Extend can be used with other interfaces such as DT ShapeArray by RST Instruments, Ackcio, or Worldsensing?
Yes, the SAAV Extend is compatible with these interfaces as the operator only needs to re-pair the SAAV Extend so that the data logger node can discover the newly added sensorized Lift Extension segments.
The SAAV Extend seems to be a larger diameter than the regular diameter SAAV. Will this affect the minimum average tilt target when you’re verifying your SAAV installation?
It wouldn’t affect the verification tool criteria as the target tilt angle for the segments is based on the inner diameter (ID) of the casing housing the SAAV, not the outer diameter (OD) of the SAAV Top Assembly.
What about the highest monitoring frequency achievable with ShapeArray?
There are a few considerations here. If you have the ShapeArray hooked up to your laptop in the field with a Field Power Unit, such as when you’re doing the installation verification, that’s when you can take the highest rate of readings because your ShapeArray is directly connected to your laptop which has extra processing power compared to a standard data logger. In that case, you’re typically looking at about one to two seconds per sample.
For long-term monitoring via a data logger, there are a few different frequency levels depending on the device and how it is configured in the system, meaning there is a variation between a direct hardwired connection from ShapeArray to the hub logger versus multiple radio nodes collecting data across a network with numerous sensors. For direct hardwired connections, a 10-minute logging frequency can often be achieved across each logger offering, with the exception of sensemetrics where they can support five-minute readings. Monitoring the instruments via a radio network with multiple nodes typically has a maximum reading frequency between 30 mins to one hour.
Is the SAAV Extend available in quarter meter (250 mm) segments?
No, the SAAV Extend is only available in half meter (500 mm) segments.
Is SAAV Extend compatible with any of the other installation kits that we offer?
SAAV Extend is currently available for vertical installations using the casing cap in 70/85 mm OD casings or the compression clamp solution which satisfies any conduit from 52-100 mm ID.
Elements of the transcript have been edited for clarity and concision.
Click to watch “SAAV Extend—Measurand’s latest Innovation” webinar on demand
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