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ShapeArray with Loadsensing: the ultimate question-and-answer list

Loadsensing’s wide integration capabilities increased in February when Worldsensing unveiled a partnership with Measurand Instruments. The initiative saw Measurand’s popular ShapeArray family of ground and structural deformation measurement products being added to the list of technologies that can be monitored easily and cost-effectively using Loadsensing data loggers.

To dig into the detail of what this means for geotechnical engineers and other customer groups, we recently held a Measurand and Loadsensing 101 webinar. Hosted by Matthew Miller, Technical Services and Instrumentation Specialist at Measurand, and Juan Pérez Arcas, Worldsensing Geotechnical Engineer and Loadsensing expert, the webinar drew a wide audience from around the world.

And they asked a mass of questions that couldn’t be answered during the sessions. Here, then, is the ultimate question-and-answer list regarding the Measurand ShapeArray and Worldsensing Loadsensing integration.

Questions

  • If we purchase a Connectivity Management Tool (CMT) Edge gateway, is the data stored only on the gateway or can it be pushed periodically to a third-party server?
  • Can the gateways be switched to mesh mode rather than being in a star topology?
  • Can we add radio repeaters over distances beyond 12 km / 7.5 miles or where there is no direct line of sight?
  • What is the price of silent or non-monitored ShapeArray segments versus regular ones? Are these segments always the same length—500 mm—or can they be longer?
  • Can the data logger use a multiplexer to measure several vibrating wire sensors?
  • Is there a monthly cost for the data logger CMT software?
  • Is there a web-based solution that can handle ShapeArray Raw2Data conversion? Is data processing still done manually using SAASuite, or can it be processed automatically using the gateway?
  • Can you install the data logger inside a flush mount below ground? Would there be any issues with the radio antenna, for example in flush mounts on road surfaces?
  • How do you address data logger readings at extreme temperatures?
  • How many in-place inclinometer segments can the Loadsensing data logger handle?
  • What is the maximum reading frequency of a ShapeArray equipped with the Loadsensing data logger?
  • Can the digital node convert the raw data into English Engineering Units?
  • How did Measurand collect data before the Worldsensing data logger integration?
  • Is communication via the cellphone network or a separate radio network? If it is a radio network, is there a monthly cost?
  • Can you power the digital logger through batteries or through an external power source?
  • What does the digital logger do during the radio coverage test? Does it look for gateways? What are the different options and how do these affect the user?
  • Is it possible to install a ShapeArray and piezometer in the same hole?
  • How do these products withstand vandalism and extreme temperatures?
  • How does the ShapeArray and Loadsensing combination work for rail geometry?

If we purchase a Connectivity Management Tool (CMT) Edge gateway, is the data stored only on the gateway or can it be pushed periodically to a third-party server?

Juan Pérez: Yes, data can be pushed periodically. Both CMT Edge (OnPrem) and CMT Cloud (cloud-based connectivity management) by Loadsensing include an FTP client that allows you to connect to an FTP server to push data from the edge automatically. Plus there are other data access options.

Can the gateways be switched to mesh mode rather than being in a star topology?

Juan Pérez: No, they can’t. Currently Loadsensing is a star topology network. The long-range star radio network is the best topology for wide-area projects in civil construction, surface mining, tailings dams, linear infrastructure tunnels, railway monitoring and so on. In some applications, particularly in underground mining, the possibility of repeating the radio messages might have some advantages. We are exploring some options to provide a solution for these particular cases.

Can we add radio repeaters over distances beyond 12 km / 7.5 miles or where there is no direct line of sight?

Juan Pérez: You can install an additional gateway to solve these situations. CMT Cloud by Loadsensing is compatible with multi-gateway deployments. With CMT Edge it is possible to deploy more than one network in the same project.

What is the price of silent or non-monitored ShapeArray segments versus regular ones? Are these segments always the same length—500 mm—or can they be longer?

Matthew Miller: Silent segments are approximately a quarter of the price of sensorized segments, and they are only used at the bottom eyebolt end of the ShapeArray.

Non-sensorized extension tubes can be used at the surface to fill the void between the top of the instrument and the top of the casing, should the zone not require monitoring.

Can the data logger use a multiplexer to measure several vibrating wire sensors?

Juan Pérez: Not currently. We have a five-channel vibrating wire logger that can read five vibrating wire sensors and their thermistors. Depending on your specific requirements, we can find a proper solution for the project. I suggest contacting our sales team and explaining your requirements, including the quantity of vibrating wire sensors per monitoring section. We will propose an option.

Is there a monthly cost for the data logger CMT software?

Juan Pérez: CMT Edge has a perpetual license cost which is bundled with every 4G gateway edge purchase, while CMT Cloud has a monthly subscription license. You can find more information about our data, device and network monitoring software options in our connectivity management section.

Is there a web-based solution that can handle ShapeArray Raw2Data conversion? Is data processing still done manually using SAASuite, or can it be processed automatically using the gateway?

Juan Pérez: Most data management and visualization software compatible with in-place inclinometers can handle the data collected by the Loadsensing solution. You need to add a step to do the conversion. All data collected by Loadsensing devices is raw data that must be converted into Cartesian engineering units by the Raw2Data software in the SAASuite.

This conversion will produce a .mat file that can be used with the Measurand visualization software. It will also produce a comma-delimited .dat file with Cartesian units and reading types (such as cumulative or incremental deviation, temperature, tilts and so on) that can be imported into any third-party data management system.

The very first execution of the Raw2Data software must be done manually, to configure settings for the project such as the instrument’s orientation, reference end, azimuth offset and so on. This manual conversion, called a reset, saves these settings so that subsequent conversions can be automated. Once the first conversion has been completed manually, the Raw2Data software can be automated with command line calls to process new readings.

Triggering the command line call to Raw2Data can be done using scheduling software such as Windows Task Scheduler. For more information, refer to Measurand’s software manual.

Can you install the data logger inside a flush mount below ground? Would there be any issues with the radio antenna, for example in flush mounts on road surfaces?

Juan Pérez: You can install the data logger inside a manhole. The two main difficulties that need to be addressed are water ingress and radio communication. The installation personnel should apply good installation practices, including:

  • Installing the node as high as possible inside the confined space, to avoid placing it in zones more susceptible to flooding.
  • Taking special care in passing the cable from the ShapeArray through the data logger cable gland.
  • Properly closing the enclosure with a torque screwdriver.
  • Applying an extra protective sealant layer if needed.
  • Guaranteeing the drainage of the manhole.

Radio coverage is reduced inside a manhole, especially when it is made of steel. Traffic-rated non-metallic covers of composites or fiberglass are the best choice for avoiding excessive mitigation of the radio signal. It’s important to apply good practices to ensure the correct performance of your monitoring solution.

How do you address data logger readings at extreme temperatures?

Juan Pérez: The operating temperature of Loadsensing data loggers is -40º C to 80º C. Our engineers verify the specs of all the components to meet this requirement. In addition, our data loggers are tested in operation in a temperature chamber across this range. Data loggers can be exposed to lower temperatures occasionally but Worldsensing can’t guarantee proper operation out of the operating temperature range.

If you are planning to expose the device for a long time to temperatures outside this range, we would need to carry out further analysis.

How many in-place inclinometer segments can the Loadsensing data logger handle?

Juan Pérez: The Loadsensing digital logger can handle up to 100 ShapeArray segments. Regarding in-place inclinometers, it depends on the model and its power requirements. In most cases, it can manage and power up to 30 in-place inclinometers. This limit is increased up to 50 in-place inclinometers for the RST Gen4 operating in Modbus Remote Terminal Unit mode.

What is the maximum reading frequency of a ShapeArray equipped with the Loadsensing data logger?

Juan Pérez: The sampling rate is from every 30 seconds up to once a day. The frequency depends on the number of segments connected to the chain, so for example for a 100-segment array the highest frequency is every five minutes.

Can the digital node convert the raw data into Engineering Units?

Juan Pérez: No, it can’t convert the raw data into Engineering Units. This conversion requires the SAASuite. We are exploring how to process the data in CMT Cloud. Contact us if you are interested in this feature because it would be useful to understand your requirements.

How did Measurand collect data before the Worldsensing data logger integration?

Matthew Miller: One year ago, all ShapeArrays required a power supply with a 12 V battery, as well as an enclosure fitted with a Campbell data logger, SAA232 interface(s), regulators, modems and so on. This setup required intensive programming and testing prior to deployment. Now, with Worldsensing, ShapeArrays can collect the same quality of data while being supported by the trusted Loadsensing LoRa network.

Is communication via the cellphone network or a separate radio network costly? If it is a radio network, is there a monthly cost?

Juan Pérez: Loadsensing system uses a LoRaWAN/LoRa radio network. When you deploy your radio infrastructure, including gateways, and add them to your project, there is no monthly cost. With CMT Cloud, the monthly fee includes the maintenance and service of the LoRa network server but there is no fee associated with the radio transmission.

Can you power the digital logger through batteries or through an external power source?

Juan Pérez: Yes, the digital logger can be powered with an internal battery. It is also possible to power it with the USB connector or using external power. Depending on the frequency of the acquisition rate, it can be a useful tool to use the USB connector to provide power extending the battery life.

What does the digital logger do during the radio coverage test? Does it look for gateways? What are the different options and how do these affect the user?

Juan Pérez: During radio coverage tests, the logger transmits 45 radio messages in different modulations. Then, the mobile app connects to the CMT software via the internet to visualize the results of the test. So, what you see in the mobile app is the arrival of the radio messages from the gateway. This is useful to make sure the installation is done properly.

Is it possible to install ShapeArray and piezometer in the same hole?

Matthew Miller: We get this question all the time. And the answer is yes. When you’re drilling a new borehole, it is common to install an inclinometer casing in conjunction with a piezometer. We routinely see piezometers secured to the exterior of the casing during the grouting process.

How do these products withstand vandalism and extreme temperatures?

Matthew Miller: We have hundreds of ShapeArrays installed in the oil sands in Alberta, which is harsh in terms of climate. The operating temperature is from -35º C to 60º C. Installation temperatures go down to -20º C, because we have clients who carry out monitoring programs throughout the winter in open-pit mines. In terms of vandalism, there are secondary enclosures to tuck away the top of the casing and the green encasing cap.

The benefit of Loadsensing digital loggers is that you are able to condense the supporting setup so what is visible looks like a standard municipality cover. When we had big enclosures with a solar panel, we had some issues. People were stealing the solar panels. But now, with batteries, it’s much easier to prevent vandalism.

Juan Pérez: In terms of vandalism, the internal batteries reduce the dimensions of the data acquisition system externally powered. And our solution allows for the possibility of installing the digital logger into a manhole, with some protection. This is an advantage not only for preventing vandalism but also for allowing ShapeArrays to be installed in surrounding zones as well as in the vicinity of the construction project itself.

In terms of temperature, all our electronics are tested from –40º C to 80º C, so we can guarantee operations in these conditions.

How does the ShapeArray and Loadsensing combination work for rail geometry?

Matthew Miller: A few years ago, ShapeArrays were starting to be deployed on railways and more specifically on the rail ties or sleepers. The horizontal ShapeArray will provide a 2D output indicating a vertical deflection along the length of the instrument. You would normally see these installed inside a steel conduit to help mitigate thermal effects, especially outdoors with regular temperature swings.

It would be secured with routing clamps, typically every meter or two, to keep a low profile, and installed in the middle or on the side of the tracks to measure the displacement of the rail bed.

Juan Pérez: Sometimes it’s an advantage to be able to deploy a chain of inclination sensors attached to the sleepers to monitor settlement and profile. On the other hand, in some projects it is also possible to just install our Loadsensing Wireless Tiltmeter, fixed to sleepers every three meters to monitor cant and twist. By doing this, the installation time can be reduced.

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