8/13/2019 ETM Sonic Extometers

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 INSTRUMENTATION – INFORMATION SHEET

UK/IRE 328-S (07-13) V2  

ENGINEERING EARTH’S DEVELOPMENT, PRESERVING EARTH’S INTEGRITY. WWW.GOLDER.COM 

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Installation of sonic anchor set

Mark IV extensometer anchorsets are designed to work intandem with the ETM sonicextometers. 

For further informationplease contact:

E-mail:instrumentation@golder.com 

John Toplis

Instrumentation Manager[+44] (0)1283 522201 jtoplis@golder.com

See our website for our fullrange of instrumentation:www.golder.com/instrumentation 

ETM Sonic Extometers

The ETM Extometer is a flexible sonic probe extensometer that allows detailedmeasurement(s) of ground movement in mine and tunnel excavations. This highlyaccurate device (±0.5mm) can measure up to 20 anchor positions in a 7m longborehole.

The instrument uses the “magnetostrictive” principle to identify the position(s) of themagnetic anchors in the borehole. Each system consists of a flexible probe andtransducer head which is connected via a cable to a portable rechargeable CANbusreadout unit. This incorporates an LCD screen displaying readings to a resolution of0.005mm.

 A single system can be used to measure strata movement at multiple locations in amine or tunnel system as the probe is only inserted into the hole when a reading is to

be taken.

Borehole accessories are low cost and simple to install. ETM Extometer systems aresupplied with probe, probe carrier, cable, readout, battery charger, manual and theExbolt data analysis and plotting software.

The ETM02 differs from the ETM01, in that the readout incorporates a facility tointernally store readings from multiple extensometer holes and download them directto a PC.

ETM Extometers are not ATEX approved and should not be used in areas where thereis a risk of an explosive atmosphere unless suitable precautions are taken to ensurethat an explosive atmosphere is not present. An independent assessment for its use

under the Provisions of Regulation 19 (2) g of the UK Electricity at Work Regulationsis included in the manual.

ETM Sonic Extometers are used to:

  Measure dilation of the strata throughout the length of a 7m hole;

  Identify the horizons where dilation occurs;

  Determine the height of failure or roof softening; and

  Demonstrate trends of strata deformation.

EXTENSOMETER

Array of Strain

Gauged Rockbolts

 

 A typical rock bolted tunnel monitoring station Typical ETM Extometer data plot

0 50 100

8

DISPLACEMENT (mm)

2 22/ JAN 98 1m3 23/ JAN 98 1m4 26/ JAN 98 8m

5 5/ FEB 98 64m

6 2/ MAR 98 124m

7 4/ APR 98 222m