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Rod Extensometers

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Rod Extensometers are used to monitor small scale rock and soil movements to a high degree of accuracy, including settlement and heave of foundations, the relaxation or subsidence of rock around tunnels, shafts, caverns and abutments. Relative movement between the end anchor and the reference tube is measured with either a dial depth gauge or a displacement transducer. The displacement transducer is installed in the reference tube and connected to the free end of the rod; the other end of the rod has one of two anchors connected.

Rod Extensometers serve to measure lengths between one or more anchor point and a reference head.

The Rod Extensometer system accurately measures settlement and/or heave between single or multiple anchor points in a borehole and at its reference head. The system employs up to eight rods, anchored along the axis of a borehole, terminating in the reference head at the borehole entrance. The Rod Extensometer is isolated from the backfill material by a protective sleeve that ensures its free movement.

There are a versatile range of options for Rod Extensometers:

• Automatic or manual reading
• Rods made from Stainless Steel or fibreglass
• Hydraulic anchoring for soil
• Groutable anchoring for rock
• Multiple or single point rod reference

Displacement along the axis of the borehole from the anchor is recorded by measuring movement of the top of the rod relative to the reference head.

The ground condition determines the type of anchor to use:

• Groutable anchors for down-hole installation in rocks
• Hydraulic type anchors (single or double ended) for soft soils
• Packer anchors for jointed rocks, where there is flowing water, or up-hole installations

The extensometers have reference heads with provision for up to eight measuring points per borehole. Borehole diameters may be in the range of 100mm-200mm. Use Stainless Steel rods for greater depth range, or fibreglass rods for quicker installation at shorter depths. A multipoint reference housing receives all rods from the one borehole installation.

Ordering Information:

E10-1.1 Groutable anchor unit; fits rods E10-2.1 to E10-2.6, includes PVC extension to fit sleeves E10-2.10 to E10-2.12
E10-1.20 Hydraulic anchor, single action; Ø75mm borehole, for use with hydraulic tubing ¼inch W6-2.9
E10-1.21 Hydraulic anchor, double action; Ø75mm borehole, for use with hydraulic tubing ¼inch W6-2.9
E10-1.22 Hydraulic anchor, single action; Ø100–200mm borehole, for use with hydraulic tubing ¼inch W6-2.9
E10-1.23 Hydraulic anchor, double action; Ø100–200mm borehole, for use with hydraulic tubing ¼inch W6-2.9
W6-2.9 Hydraulic tubing; black, ¼inch, priced per metre
W6-3.20 Male quick release coupling; ¼inch
W6-3.5 Spare nut and olive; Enots ¼inch
W6-3.7 Straight coupling; Enots ¼inch, for in-line hydraulic tube connection and repair
E10-3.17 Hydraulic hand pump; includes female quick release coupling and pressure gauge
P8-3.8 Hydraulic oil; priced per litre

Rods and Sleeves
E10-2.1 Extensometer Stainless Steel rod; 1 metre length
E10-2.2 Extensometer Stainless Steel rod; 2 metre length
E10-2.3 Extensometer Stainless Steel rod; 3 metre length
E10-2.4 Extensometer fibreglass rod; 1 metre length
E10-2.5 Extensometer fibreglass rod; 2 metre length
E10-2.6 Extensometer fibreglass rod; 3 metre length
E10-2.10 Protective sleeve; 1 metre length
E10-2.11 Protective sleeve; 2 metre length
E10-2.12 Protective sleeve; 3 metre length

Range Adjustment Unit for Manual Reading
Stainless Steel tube with internal thread. Provides 150mm adjustment
E10-2.13-1 For Stainless Steel rods
E10-2.13-2 For fibreglass rods

Rod Adapter Unit for Remote Reading
E10-2.14-1 For Stainless Steel rods
E10-2.14-2 For fibreglass rods

Head Fixtures
E10-3.1 Single rod reference head; manual reading
E10-3.2 Single rod reference head; remote reading
E10-3.3 Multiple rod reference head; up to 8 rods, manual reading
E10-3.4 Multiple rod reference head; up to 6 rods, remote reading

Installation Equipment
E10-4.12 Installation tool kit; tool box includes hand drill, 1.5mm diameter drill, knife, steel rule, screwdriver, mole grips, file, 6mm Allen key, spanner 12/13mm, adjustable spanner, combination pliers, junior hacksaw and spare blades
W3-4.8 Tube cutter
E10-4.4 Range adjustment tool; nut spinner to adjust E10-2.13 for manual reading
E10-4.5 Range adjustment placing tool; for adjusting E10-2.13-1 and E10-2.13-2
E10-4.6 Sleeve support/clamp unit – manual reading; for reference head E10-3.3, at least one required as installation tool
E10-4.7 Sleeve support/clamp unit – remote reading; for reference head E10-3.4, at least one required as installation tool
E10-4.8 Grout pipe; 19mm OD nylon braided PVC hose, priced per metre
E10-4.9 Air bleed/grout return pipe; 5/16in OD PVC pipe
W6-4.1 PVC adhesive – 250ml; sufficient for approx. 150 joints
W6-4.2 Metal adhesive; for securing threaded joints, sufficient for approx. 200 joints
W6-4.4 Polyester resin cartridge; 150ml, to fix anchor into drill hole
W6-4.5 Cartridge injection tool
W6-4.6 PVC cleaner; to prepare joints of sleeves, sufficient for approx. 200 joints

Connecting Cable and Fittings
CA-3.1-4-IC Instrument cable, 4 core, 7/0.20, screened; polyurethane jacket, priced per metre
CA-2.3-12-SC 12 core, multicore cable, 16/0.20, screened; PVC jacket, priced per metre
CA-2.3-25-SC 25 core, multicore cable, 16/0.20, screened; PVC jacket, priced per metre
CA-4.1 Joint sealing kit
CA-4.2 Coloured adhesive tapes; set of 10No.
CA-4.3 Crimping tool
CA-4.4 Crimping sleeves; set of 100No.
W6-6.1 Nylon ties; 150mm x 3.5mm, pack of 100No.

Readout Equipment
E10-6.1-50 Dial depth gauge; range 50mm
E10-6.1-100 Dial depth gauge; range 100mm
E10-6.2 Digital depth gauge; range 25mm
E10-6.5-T Vibrating Wire displacement transducer; range 30mm with thermistor and termination cable to reference head
E10-6.3-T Vibrating Wire displacement transducer; range 50mm with thermistor and termination cable to reference head
E10-6.4-T Vibrating Wire displacement transducer; range 100mm with thermistor and termination cable to reference head

MAN-12 Rod Extensometer
MAN-144 Rod Extensometer with Vibrating Wire Displacement Transducer