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Magnetic Extensometers

Take a look at our Technical Notes on Magnetic Extensometers The Geosense® GEO-XM settlement system is a magnet extensometer system used typically to monitor settlement and heave in foundations, excavations and embankments. Data received identifies the depth and position where settlement has occurred as well as the total amount of settlement. It […]

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Take a look at our Technical Notes on Magnetic Extensometers


The Geosense® GEO-XM settlement system is a magnet extensometer system used typically to monitor settlement and heave in foundations, excavations and embankments.


Data received identifies the depth and position where settlement has occurred as well as the total amount of settlement.


It can also be installed behind retaining structures, such as sheet piles and slurry walls, and above underground openings, such as tunnels and shafts. 


The system comprises a central access tube along which magnetic targets are positioned at various locations. Settlement is measured by the relative position of the magnetic targets using a Reed Switch Probe lowered down through the central access casing.


There are several variations to suit individual applications:


  • GXM-100    Central access tubing and spider magnets for use in boreholes
  • GXM-100P  Central access tubing and settlement plates for use in fill
  • GXM-100T  Central access tubing with telescopic joints for larger movement
  • GXM-200    Combined settlement/heave and inclination using inclinometer casing as the access tubing with spider magnets
  • GXM-200P  Combined settlement/heave and inclination using inclinometer casing as the access tubing with settlement plates
  • GXM-200T Combined settlement/heave and inclination using inclinometer casing with telescopic joints for larger movement
  • GXM-300 Central access tubing de-bonded by an outer corrugated pipe with magnetic targets
  • GXM-300i Combined settlement/heave and inclination using inclinometer casing as the access tubing de-bonded by an outer corrugated pipe with magnetic targets