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INSTRUMENTED ROCKBOLTS Strain Gauged Rockbolts and Flexible Bolts (SG series) Strain gauged rock bolts are used to measure the distribution of bolt loads in fully encapsulated systems. Nine pairs of diametrically opposed strain-gauges are mounted within the rockbolt to provide both axial and bending strain profiles. Standard lengths for our strain gauged rock bolts are 1.8, 2.1 and 2.4 metres. Other lengths can be supplied to order. Strain gauged flexible bolts are available up to 5m length. The equipment includes a 10 metre multicore cable with terminations to suit the intrinsically safe strainmeter (SG1041). Data from our strain gauged bolts can be stored and analysed using the "Exbolt for Windows" software package. RMT strain gauged rockbolts and flexible bolts provide a valuable tool for monitoring support performance against design specification. They are suitable for local or remote reading in hazardous atmospheres. RMT has many years experience in the successful manufacture, supply and installation of high quality strain gauged rockbolts. Most designs of rockbolt and ground anchor can be instrumented. Our products are rugged and proven in harsh mining and civil engineering environments. Over 450 per year are typically used in UK coal mines.
"Sentinel" Integrity Monitoring Rockbolts and Flexible Bolts (BIM series) The "Sentinel" Integrity Monitoring range of reinforcement products is a new concept in rock bolting safety. The "Sentinel" is a modified reinforcement tendon which can signal to mine management whether it is broken and, if so, where. Bolt failure can occur due to overloading and/or corrosion, and when it occurs, it can be difficult to detect. Once installed, a "Sentinel" bolt is read by inserting a simple probe connected to a strain meter into an environmentally protected sleeved socket at the end of the bolt. The strain meter reading gives a direct indication of bolt integrity. If a broken "Sentinel" bolt is detected, a non-intrusive means of accurately determining the position of the break is then available.
Intrinsically Safe Strain Meter The intrinsically safe strain meter (SG1041) is especially suited for use with RMT strain gauged rockbolts and flexible bolts. It is designed for reading multiple, quarter bridge, 120 ohm strain gauge circuits and includes all necessary bridge completion electronics. It is also ideal for use with our "Sentinel" bolt products and our remote reading extensometers. RMT are sole worldwide agents for the intrinsically safe strain meter.
Intrinsically Safe "Magnesonic" Extensometer System This is a high accuracy, 20 point, intrinsically safe extensometer system which uses a flexible probe to locate magnetic anchors by time-lapse measurement of a sonic pulse. When in use, the flexible probe and transducer head are connected to a portable battery powered readout unit with a liquid crystal display reading directly in millimetres. A single system can be used to measure strata movement at multiple locations, since the system is fully portable and the probe is only inserted in the borehole when a reading is required. Associated hole furnishings are low cost and simple to install.
General Application Extensometers RMT offers a wide range of extensometers from the simple to the "state-of-the-art". Applications range from simple visual safety devices to detailed rock deformation profiles. Advice, installation and monitoring services are available to help in all aspects of extensometer selection and use.
Wire Extensometers RMT supplies a wide range of simple to use, low cost wire extensometers. These are available with a range of hole termination systems and environmental protection provisions.
Remote Reading Wire Extensometers RMT's remote reading wire extensometer (1 to 8 wires) incorporates a constant-tension device and can be used with a variety of interfaces including the Intrinsically Safe Strainmeter (SG1041).
Reed-Switch Extensometers This uses a probe with a magnetic switch to locate magnetic anchors. It has a lower resolution than the "Magnesonic" system (+/- 1mm) but offers the capability of reading a large number of anchors in somewhat longer holes.
Resistance-Wire Extensometers High accuracy
(+/- 25 microstrain), resistive strain-gauge output, in sealed bays
0.5 to 4 metres long. Several bays may be grouted in, end-to-end.
Single bays may be point-anchored. Choice of readout devices includes
the SG1041 intrinsically safe strainmeter. RMT are sole UK distributors.
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