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Crack Meter
Kingmach Crack Meter 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 Meter
In foundation pit and deep excavation projects, Crack Meter are used to watch retaining walls, soldier piles, soil nails, nearby pavements, basement walls, and adjacent structures as excavation stages remove support from the ground. The main site concern is not only how far one point moves, but whether movement grows after each excavation layer, support installation, dewatering step, or backfill stage. Kingmach JMDL-32XXAT single-point bedrock meters can measure embedded displacement at a selected reference layer, while JMDL-22XXAT crack gauges follow opening at nearby structures or retaining elements. JMDL-52XXADT differential meters provide high-resolution relative movement at joints or structural interfaces, and JMLS-22XXADT wire rope sensors can cover longer exposed paths where access is available. A useful pit monitoring plan records excavation depth, support timing, groundwater level, construction vibration, and surrounding building observations beside each displacement curve. This helps engineers distinguish bracket disturbance from real ground movement, and it supports faster decisions when a wall, road edge, or adjacent building begins to respond to excavation. During review, the same point should be compared with nearby settlement, tilt, support force, groundwater, and inspection notes so the movement is interpreted as part of the excavation behavior rather than as a single isolated value. during maintenance.
The future of Crack Meter
The future of Crack Meter will include more mixed measurement packages rather than single-sensor orders. A slope package may combine GNSS, multipoint displacement, crack gauges, pore pressure, rainfall, and tilt. A bridge package may combine differential displacement, strain gauges, load cells, accelerometers, temperature, and bearing inspection records. A tunnel package may combine multipoint displacement, convergence, lining strain, water pressure, and vibration. Kingmach already provides a broad product ecosystem across displacement, strain, load, settlement, tilt, environmental monitoring, acquisition equipment, cables, and software. The next step is project-specific packaging where the displacement instrument is selected together with its data logger, cable, cabinet, communication route, warning logic, and maintenance plan. That approach reduces mismatched hardware and makes the monitoring system easier to operate after handover. It also helps procurement teams compare complete monitoring functions instead of comparing sensor names alone. For complex infrastructure, the package should define which movement point answers which engineering question before hardware is ordered.
Care & Maintenance of Crack Meter
For formwork and construction-stage Crack Meter, 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 Crack Meter
For procurement teams, Crack Meter should be matched to the way movement actually happens. Linear joint travel, crack width change, formwork settlement, rock layer slip, geogrid strain, hydraulic cylinder position, and long span cable pull are not the same measurement task. Kingmach's JMDL-52XXADT differential displacement meter lists 20 mm, 50 mm, and 100 mm ranges with 0.01 mm resolution, plus RS485 output and low temperature drift. The JMLS-22XXADT wire rope sensor reaches 500 mm, 1000 mm, and 2000 mm ranges with 0.1 mm resolution and IP67 sealing. The JMDL-49XXAT formwork meter is built for construction sites with IP68 protection and a 30-year designed service life. A good specification therefore starts with travel distance, mounting access, water exposure, signal distance, power supply, and whether the point must remain readable after construction equipment leaves the site. 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 Meter 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
Matthew Garcia
Instrumentation cables are durable and perform well even in harsh environments. Will definitely order again.
Daniel Brown
Excellent environmental monitoring sensors. The data is consistent, and the system integrates smoothly with our existing setup.
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