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crack gauge

Kingmach crack gauge include the JMDL-31XXAT Smart Multipoint Displacement Meter for tunnels, rock slopes, foundation pits, and surrounding rock layers. This product is not used like a surface joint gauge. It is built for boreholes where movement must be separated by depth. The instrument group includes displacement gauges, PVC measuring rod protective tubes, anchor heads, and multipoint installation kits that support three to five points. During installation, the borehole is prepared, anchor heads are set at selected layers, and grouting fixes each anchor to its target rock or soil zone. Listed models include 50 mm, 100 mm, and 200 mm ranges, all with 0.01 mm resolution. The sensing circuit changes output frequency as the measuring rod moves through the coil, so each channel can report how one anchored layer moves relative to the reference head. This layout is useful when tunnel crown movement, slope slip, or foundation pit deformation may start at one depth before it appears elsewhere. Field records should emphasize borehole number, anchor depth, grout condition, channel order, and the direction of expected movement. During later review, engineers can compare shallow and deep anchors to judge whether the deformation is local relaxation, progressive sliding, or full-section movement. That layered view is the main reason to use a multipoint instrument instead of several unrelated surface gauges.

Application of  crack gauge

Application of crack gauge

In slope and landslide monitoring, crack gauge are used to detect surface creep, deep sliding, retaining wall movement, crack expansion, and displacement between fixed reference points. The challenge is that slope movement may be slow for weeks and then accelerate after rainfall, excavation, blasting, or traffic vibration. Kingmach JMDL-31XXAT multipoint meters can anchor several depths and separate shallow movement from deeper rock layer displacement. JMDL-32XXAT bedrock meters provide single-point embedded measurement with 50 mm, 100 mm, and 200 mm ranges, 0.01 mm resolution, 0.5%FS accuracy, and -30 degrees Celsius to +80 degrees Celsius operating temperature. JMLS-22XXADT wire rope sensors support 500 mm to 2000 mm movement paths with IP67 sealing. When these readings are reviewed with rainfall, pore pressure, tilt, and GNSS data, engineers can identify whether the slope is stable, creeping, or moving toward a warning threshold. During operation, the monitoring team should keep the baseline, temperature, inspection notes, and nearby sensor behavior in the same review file. This makes it easier to tell whether a movement trend comes from normal service, a repair event, changing load, water influence, or developing structural risk. Clear records also help owners decide when a field inspection is needed instead of waiting for visible damage.

The future of crack gauge

The future of crack gauge

The future of crack gauge will be shaped by connected monitoring rather than isolated field readings. Kingmach products already include digital detection, RS485 communication on selected models, built-in memory, stored calibration data, and compatibility with automatic acquisition systems. The next practical step is cleaner connection between the sensor identity, the monitoring point, and the platform curve. A displacement value should arrive with its model, serial number, range, calibration coefficient, zero value, temperature, and installation position. That will reduce channel errors and make later review faster. In bridges, tunnels, dams, slopes, and foundation pits, future systems will compare displacement with strain, load, tilt, settlement, rainfall, water level, and construction events. Warnings will depend less on a single limit and more on the pattern of movement across several related sensors. 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 crack gauge

Care & Maintenance of crack gauge

For draw-wire crack gauge, the cable path is the part that most often decides data quality. Kingmach JMLS-22XXADT wire rope sensors use a plastic-coated stainless steel cable, spool, precision rotary sensor, RS485 communication, IP67 sealing, and ranges up to 2000 mm. During installation, align the cable with the expected movement direction, keep the pull smooth, and avoid rubbing against concrete edges, steel corners, temporary supports, or moving machinery. Do not overextend the cable beyond its range, and do not let it snap back during inspection. Check the anchor point, cable coating, spool movement, connector sealing, and lightning protection after storms or heavy site work. For long-term dam, tunnel, slope, or machinery monitoring, include cable tension and cable path photos in routine maintenance records. A clean cable route gives more reliable displacement data than any later software correction. 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 crack gauge

In structural monitoring, crack gauge should not be treated as single-purpose accessories. Kingmach displacement products can work with comprehensive testers, automatic acquisition systems, bus modules, RS485 output, and monitoring software, which allows movement data to sit beside strain, load, settlement, tilt, vibration, temperature, and water level. That combined view is important because displacement often has several causes. A tunnel crown reading may respond to excavation sequence, groundwater, lining age, or nearby traffic. A bridge joint may move with both temperature and bearing behavior. A slope reading may change after rainfall, blasting, or retaining wall loading. By using smart products with stored parameters and digital transmission, project teams reduce channel mix-ups and make later data review cleaner. The result is a monitoring chain where field installation, sensor identity, baseline readings, and platform curves can be checked against one another. 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: What are crack gauge used for?
    A: They measure movement such as relative displacement, crack width, expansion joint travel, bedrock deformation, rock layer movement, geogrid deformation, formwork settlement, and equipment stroke.

    Q: Which Kingmach models belong to this category?
    A: Common models include JMDL-21XXAT, JMDL-22XXAT, JMDL-24XXAT, JMDL-31XXAT, JMDL-32XXAT, JMDL-49XXAT, JMDL-52XXADT, JMCW-21XXADT, and JMLS-22XXADT.

    Q: What range should be selected first?
    A: Start from the expected movement. Short joint monitoring may need 20 mm to 100 mm, while draw-wire or equipment travel may require 500 mm to 2000 mm.

    Q: Can these products support remote monitoring?
    A: Yes. Several Kingmach models support digital transmission, RS485 communication, automatic acquisition, integrated testers, or unattended monitoring systems.

    Q: Why is the baseline reading important?
    A: All later movement is compared against the starting point. The baseline should be recorded after the sensor, bracket, anchor, cable, and structure are stable.

Reviews

Andrew Lee

The visualization software is intuitive and powerful. It helps us analyze monitoring data efficiently.

James Thompson

The tiltmeters and accelerometers are very sensitive and provide precise data. Perfect for our structural health monitoring system.

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