Rod Extensometers serve to measure lengths between one or more anchor point and a reference head. Relative movement between the end an anchor and the reference head can be measured with either a depth gauge or a displacement transducer inserted through the reference head and registering on to the free end of the rod. Rods are individually isolated by a plastic sleeve. They ensure high precision monitoring, even at great installation depths or lengths. Extensometer measuring rods are supplied in either Stainless Steel or as a continuous length of fibreglass rod.

Extensometers using stainless steel rods (supplied in 1, 2 or 3 metre lengths) must be assembled on site. Stainless steel rods in general are stiffer than fibreglass rods and are therefore preferred when compression rather than extension is likely or when larger lengths of rods are required. Furthermore stainless steel rods are easily adapted in length when the exact installation depths are not known at time of order.

Extensometers using continuous fibreglass rods can be pre-assembled at the factory, coiled and shipped to the site, ready for installation. In general fibreglass rods are easier to install in confined areas such as tunnels and are preferred over stainless steel in alkaline environments.

Typical areas of application include the monitoring of:

• Movements of rock and soil, caused by fractures, landslides and weathering
• Underground settlements and deformations of foundations and abutments, as well as man-made caverns
• Relaxation and deformation of rock around tunnel walls, shafts, pillars, roofs and caverns
• Commonly used in boreholes
• Suitable for short or long term monitoring

Please request Manuals through info@itm-soil.com.au