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Fixed extensomete

Fixed extensometer is usually defined as a device placed in embankment fill or inside a borehole for monitoring settlement or heave between two points, without using a removable probe.

The settlement platform or the tell-tale extensometer can be used on a string of settlement rods. These are, respectively, connected to a plate buried at the embankment foundation level or to a datum point grouted inside the borehole in firm soil.

Optical levelling of the top of the riser rod provides precise monitoring. Electrical transducers can be used for automatic remote readings even for inaccessible locations..

Technical specifications

The primary advantage of the settlement platform is its simplicity. The settlement platform consists of a galvanized square plate to which a riser settlement rod is attached. Anti-friction corrugate pipe is placed around the riser rod. Optical levelling measurements, on the survey point mounted on the top cap, provides records of plate elevation..
0D100A20000  2M Section riser rod
0D111PV5500  Corrugate pipe, 0D 55mm
0D100B05000  Square plate 500x500mm
0D100T15000  Top cap and survey pointА

The tell-tale extensometer is a single-point extensometer which is, typically, used for precise monitoring of ground surface settlement or heave. It consists of a stainless steel bottom anchor to which a string of riser measuring rods is attached. Anti-friction corrugate pipe is placed around the riser rods. Optical levelling measurements of the top head of the riser rod provides a measure of ground settlement. Sliding rings are located at both ends in order to prevent down drag forces on the rod..
0D100A20000 0M section riser rod
0D111PV5500 Corrugate pipe, 0D 55mm
0D100TT6000 Bottom anchor
0D100TT0100 Top cap and survey point
0D100TTEL10 DTM Measuring head

DTM electrical transducers can be mounted on either settlement platforms or the tell-tale extensometers..
Range 250mm, 500mm, 1000mm
Total accuracy 0.25% FS
Output signal 4-20mA

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