The Single Point Model EX-1 is an inexpensive, simple, rugged, and reliable device to monitor deformation in under ground workings such as chambers, tunnels, mine galleries and mine excavations. The entire instrument is recessed in the borehole, providing maximum protection against mechanical damage. In situations where boreholes may be easily drilled, it may be preferable to install several EX-1 extensometers rather than a multiposition extensometer. Deformation measurement is accomplished by using either an analog or digital depth indicator to measure the position of the rod tip relative to the collar anchor reference surface. The Double Point Model EX-2 is similar to the Single Point EX-1 although two anchors are employed. The use of two points allows the engineer to distinguish between dangerous deep seated movements and more trivial surficial spalling. The extensometer assembly consists of modified expanding shell rockbolt anchors set with a socket wrench. The downhole anchor is connected to a 1/4 inch rod which moves inside the uphole anchor’s 1/2 inch pipe. Both anchor rods terminate in the collar anchor, which is set in the mouth of the borehole. Anchor position is measured with either an analog or digital depth indicator to measure the position of each rod tip relative to the collar anchor reference surface.

RST Instruments Ltd.
11545 Kingston St.,
Maple Ridge, BC
Canada V2X 0Z5
Telephone: 604 540 1100
Facsimile: 604 540 1005
info@rstinstruments.com
www.rstinstruments.com