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GNSS
Kingmach GNSS include the JMDL-31XXAT Smart Multipoint Displacement Meter for tunnels, rock slopes, foundation pits, and surrounding rock layers. The product uses displacement gauges, PVC measuring rod protective tubes, anchor heads, and multipoint installation kits that support three to five monitoring points. Installation is performed by drilling and grouting, with anchor heads fixed at different depths so each layer can be observed separately. Listed models include 50 mm, 100 mm, and 200 mm ranges, all with 0.01 mm resolution. The sensing principle uses an LC oscillation circuit: as the measuring rod moves inside the coil, magnetic reluctance and inductance change, causing the output frequency to change in a linear relationship with displacement. Because the rod and coil work without contact, the structure is less vulnerable to mechanical damage during installation. The built-in memory stores model, serial number, calibration coefficients, and up to 600 measurement records for later traceability. During project setup, the measuring point should be matched with the expected travel direction, available mounting space, cable route, and required acquisition interval. This prevents a short-range joint instrument from being used on a long-travel point, or an exposed sensor from being placed where an embedded anchor is needed. It also helps the monitoring team set a baseline that can be defended during acceptance and later maintenance review.
Application of GNSS
In integrated structural health monitoring, GNSS act as the movement layer inside a wider measurement network. Their role is to show where a point has shifted, how fast the shift is developing, and whether the change agrees with other instruments. Kingmach displacement products can feed digital records into acquisition units and monitoring platforms, while related Kingmach product groups provide strain, load, settlement, tilt, vibration, pore pressure, water level, rainfall, data logging, cables, and software. A practical system may use JMDL-52XXADT meters for precise joint travel, JMDL-31XXAT meters for rock layers, JMDL-24XXAT meters for buried geogrid deformation, and JMLS-22XXADT sensors for longer cable travel. The data chain should define point names, units, zero values, sampling intervals, warning grades, and inspection actions before alarms are enabled. This prevents a displacement curve from becoming an isolated chart. Instead, the reading can be checked beside force, strain, settlement, temperature, rainfall, and construction records, giving engineers a clearer basis for maintenance and warning review. During commissioning, each curve should be verified against the physical point so later reports can be trusted by site teams, designers, and owners. The same record should also note cabinet number, logger channel, cable tag, power supply, and communication route, because many long-term data problems begin outside the sensor body.
The future of GNSS
The future of GNSS in infrastructure will depend on better integration with digital twins and asset management records. A displacement reading becomes more useful when it is tied to a drawing location, construction stage, material zone, inspection photo, and repair history. Kingmach products such as JMDL-31XXAT multipoint meters and JMDL-32XXAT bedrock meters can represent movement at depth, while JMDL-52XXADT differential meters and JMDL-22XXAT crack gauges represent surface or joint movement. Future platforms can map these readings onto tunnel sections, dam galleries, bridge joints, or slope profiles, allowing engineers to see where deformation is growing. This is especially useful when movement is small but repeated. A millimeter trend may not seem urgent in one report, but over months it may show a clear relationship with rainfall, traffic, excavation, or water level. The strongest systems will still depend on careful installation, because digital tools cannot correct a loose bracket, wrong range, or poorly recorded baseline. Clear reporting will make displacement monitoring more useful for non-specialist decision makers while preserving the detail engineers need.
Care & Maintenance of GNSS
For formwork and construction-stage GNSS, inspection frequency should match the work rhythm. Kingmach JMDL-49XXAT formwork displacement meters may be used during concrete pouring, steel pipe support monitoring, tunnel portal movement, slope sliding, dam displacement, or railway subgrade monitoring. The product lists IP68 protection, 0.01 mm sensitivity, 0.5%FS accuracy, and a 30-year service life, but construction sites can still damage connectors, brackets, and cables quickly. Before pouring, confirm the zero reading, bracket tightness, cable route, warning level, and acquisition interval. During pouring or loading, watch for sudden jumps that match pump movement, support adjustment, or worker contact. After the stage is complete, inspect whether the sensor was knocked, buried, or moved. Keep time and temperature records with displacement readings because short-term construction movement can be different from long-term structural deformation. Keep the installation photo, point number, zero value, and expected movement direction with the commissioning record for later review. If a reading changes after maintenance work, inspect the base, anchor, cable, and cabinet before assuming the structure itself has moved.
Kingmach GNSS
Long-term projects need GNSS that can survive the same weather, vibration, cable pulling, and site handling as the structure itself. Kingmach designs several smart displacement products with built-in memory chips, digital detection, strong anti-interference capability, and direct display through compatible testers. The JMDL-22XXAT crack gauge stores up to 600 measurement results and covers 20 mm, 50 mm, 100 mm, and 200 mm models. The JMDL-21XXAT general-purpose model stores up to 800 records and can save time, temperature, absolute displacement, relative displacement, and zero-point values. These records matter during handover because the original baseline, later shifts, and abnormal readings can be checked without relying only on handwritten notes. For bridges, dams, tunnels, slopes, and buildings, that traceability helps maintenance teams judge whether a movement event is isolated, repeated, or linked with surrounding construction and environmental change. The point should be named on the drawing, linked with its cable route, and checked against the expected movement direction before the first automatic reading is accepted. For daily review, the reading should be compared with nearby points, recent weather, site operations, and any loading event that could explain the movement.
FAQ
Q: Which GNSS are used for rock layers or bedrock?
A: JMDL-31XXAT multipoint meters are used for different surrounding rock layers, while JMDL-32XXAT single-point bedrock meters are used for tunnel rock mass, dam bedrock, slope, or foundation pit movement.
Q: How many points can the multipoint meter support?
A: The multipoint installation kit supports three to five monitoring points, with anchor heads fixed at different depths by drilling and grouting.
Q: What ranges are listed for these models?
A: Both JMDL-31XXAT and JMDL-32XXAT list 50 mm, 100 mm, and 200 mm models with 0.01 mm resolution.
Q: Why monitor several depths?
A: Different layers may move differently. Separating shallow and deep movement helps engineers judge whether the problem is surface creep, deeper rock slip, or overall mass movement.
Q: What records should be kept?
A: Keep drilling depth, anchor location, grouting date, channel name, zero value, cable route, and first stable reading.
Reviews
Robert Taylor
The weir flow meter is well-built and delivers accurate measurements. Great value for water management applications.
Michael Anderson
The strain gauges and load cells are extremely accurate and stable. They performed very well in our bridge monitoring project. Highly recommended!
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