settlement markers - geosmartgeosmart.com.sg/technical/geotechnical_instruments.pdf · settlement...
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SETTLEMENT MARKERS The settlement marker is used to measure a localised settlement or heave of roads, slopes,
embankments, utility pipes and cables.
INSTALLATION AND MONITORING
Concrete Nail
Concrete Nail
Painting
Concrete Structure
50mm
Schematic diagram of installed settlement marker in soil
Schematic diagram of installed settlement marker on concrete
Cross‐section of Utilities/Services 10 cms
Backfill soil
75 mm dia Heavy duty PVC pipe with Cap
16 mm dia mild steel rod
50x50x4mm steel plate
Varied
Len
gth
Backfill soil
Schematic diagram of installed settlement marker on utility
Settlement Marker on Concrete Installed on a Pavement
Settlement Marker for Utility services Settlement Marker in Ground
The monitoring of settlement marker is carried out by leveling survey and readings are taken at regular intervals to
check any settlement or heave.
800 minim
um
100Ф PVC or Steel Tube
Convex End
Sand Fill
75 mm Ф hole filled with cement grout after placing‐in the steel rod.
25Ф Steel rod
Concrete to be painted in yellow
Concrete
GROUNDWATER STANDPIPE Measures fluctuation of ground water level. It is used as part of a system for early detection
of water loss that could cause ground settlement.
INSTALLATION
MONITORING
Schematic diagram of ground water stand pipe
Bottom Cap
Ground Level
Protective Cover
Coarse Grain Sand
Bentonite Pellets
Perforated PVC Pipe
Water level indicator
A cap and protective box is placed over the water standpipe tube opening to prevent disturbance.
Ground water level is measured by using water level indicator. The probe of water level indicator is lowered down into the water standpipe until light or buzzer indicates contact with the water. Depth to water level is measured from the measuring tape attached to the indicator.
VIBRATING WIRE PEIZOMETER Measures changes in the ground water pressure at different depths. It is used as part of a system for early detection of change in water pressure that could cause ground settlement.
INSTALLATION
To terminal
Coarse Grain Sand
Ground Level
Grout
Bentonite Pellets
Electric Cable
Vibrating wire Piezometer tip
Vibrating wire piezometer tip
Schematic diagram
The borehole with vibrating wire piezometer installed is kept in a protective metal box to prevent damage & disturbance to the instrument.
MONITORING
Vibrating wire piezometer
data logger
The vibrating wire piezometer is connected to the read out unit and the ground water pressure readings are recorded and stored in the data logger
INCLINOMETER Measures lateral movements of the ground, retaining walls and piles for early detection of
any disturbance or effect to structures and property due to construction activity.
INSTALLATION
MONITORING
The inclinometer probe is lowered down in to the casing and at every 0.5 m intervals it records the lateral movement. The raw data obtained is transmitted from the inclinometer probe to a read out or a PDA by Bluetooth technology.
After the installation of inclinometer casing in the hole, the casing top is capped to prevent the entry of foreign particles.
Metal protective boxes are used to prevent the instruments from being disturbed. Instrument identification is affixed on to the box.
Schematic diagram of inclinometer casing
Grout
Protective cover
Ground Level
Bottom
Inclinometer casing
Inclinometer probe
Cross section view of inclinometer probe inside the casing during monitoring works
MAGNETIC EXTENSOMETER Measures settlement of the ground at various depths for early detection of any disturbance
or effect due to construction activity.
INSTALLATION
MONITORING
The magnetic extensometer probe is lowered down into the casing untill light or buzzer indicates the contact with the spider magnet. Depth of the magnet is measured from the measuring tape attached to the probe.
Installed casing is capped and kept in a protective metal box to prevent damage & disturbance
Schematic diagram of magnetic extensometer
Magnetic extensometer probe & spider magnet