Liquid Settlement System
The Geosense® VWLSS-200 Vibrating Wire Liquid Settlement System is used to monitor settlement or heave in soils and other structures such as embankments, earth and rockfill dams.
The main components are a reservoir (single or multiple), liquid-filled tubing and a vibrating wire pressure transducer cell mounted on a plate or, for borehole application, attached to an anchor.
The vibrating wire sensor is attached to a settlement plate at the point of estimated settlement. The sensor is connected via two liquid-filled tubes which are connected to a reservoir located on stable ground.
As the transducer settles with the surrounding ground the height of the column is increased and the corresponding higher pressure is measured by the transducer.
Settlements are calculated by converting the pressure to millimetres of liquid head.
Rod Settlement System
Geosense® GEO-XR single point rod settlement system is used to monitor sub-surface settlement or heave of ground.
The system comprises a series of inner steel rods and plastic outer sleeves together with plates when positioned on ground before fill or Borros type anchors when used in boreholes.
The inner steel rod is made from heavy duty 1metre lengths of 25mm outside diameter with a 3/4” BSPM thread with external socket.
The outer plastic sleeves in 1metre lengths can be 60mm (2”) or 165 mm (6”) diameter with flush threads so that the inner and outer rod can be extended together.
A circular or square thick steel plate with a 3/4” BSPF socket welded onto it allows the datum plate to be placed and the first inner rod connected. Outer sleeves are placed over the steel rods as filling occurs.
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
VW Settlement Profiler
The Geosense® Vibrating Wire Settlement Profiler is used for the measurement of subsurface settlement.
Working principle: A vibrating wire sensor is located within a probe that can be pulled through a buried pipe or borehole. The sensor is connected via a liquid-filled tube mounted on a reel which is mounted horizontally at the reservoir location on stable ground. The reel is free to turn as the probe is pulled through the pipe or borehole.
The sensor measures the hydraulic head of liquid between the sensor and the reservoir locations.