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STRATA MOVEMENT INDICATORS Visual Telltales (Single, Dual and Triple Height) RMT's range of telltales are low cost, easily installed safety monitoring devices for indicating tunnel stability. The visual dual height telltale has become the industry standard. The great advantage of the dual height indicator is that it allows movement above and below the rockbolted horizon to be distinguished at a glance. This provides underground workers with instant information on roof condition and operational management with roof deformation history and advance warning of remedial action requirements. In many countries, RMT telltales are installed and read on a routine basis to provide a reliable roof control management system. RMT telltales are installed as mandatory safety devices in UK coal mines. The system is patented in the UK, USA, Australia, China, Poland, and Canada. Dual height telltales are designed for reinforced rock, providing a differential strata-movement indication based on patented concentric indicators. The two sets of reflective coloured bands indicate roof movement within and above the reinforced height. The millimetre scales also allow accurate monitoring of movement trends. Triple height telltales are designed for use where two different lengths of reinforcement are installed. Windows software, 'Telltale for Windows', is available from RMT for recording, presentation and analysis of telltale data. Telltales can be supplied with copper or plastic reference tubes including a water-diverting version for wet conditions. Stainless steel spring-anchors and multi-strand suspension cables are used throughout for corrosion protection. A standard range colour-codes and wire-lengths is stocked - others are available to order.
Remote Reading Telltale System With the new Remote Reading Telltale System, RMT has extended the telltale concept to provide a full remote-reading capability. Up to 400 telltales can now be integrated at low cost into a mine-wide monitoring system to provide highly accurate, real-time and historical data on roof condition on a surface PC. The system allows up to 100 dual height telltales to be strung together along each of 4 separate tunnels in a 'daisy chain' configuration using a simple, low cost, twin core connection cable. As each tunnel excavation advances, new transponders can be added, with the trailing cable crimped to the leading cable from the last telltale. At the other end of the chain of transponders, the cable is connected to an underground power supply, interrogation and communications unit. The system automatically sends data to a surface PC, using a standard twisted wire pair, and provides local interrogation and diagnostic facilities. A single PC can be used to monitor up to 4 sub-systems of remote reading telltales. The surface PC software has been written to provide a simple user friendly interface. The standard display provides information on the current reading and recent history of all connected telltales. Individual warning and action levels can be set for each telltale, both as absolute levels or rates of change. The software provides an archiving facility to allow a subset of the data to be stored for later access via RMT’s standard Telltale for Windows package. The system also provides automatic recognition of new telltales as and when they are added to the system. Transponder scanning rate is user selectable, with a maximum rate of one every 10 seconds. The system has been designed with reliability and fault tolerance as core requirements. A highly reliability, frequency-based low power telemetry method is used to address and interrogate each transponder. The transponders can be installed and connected up by the mining workforce using a simple crimp connection without the need for specialist engineers. In addition to the visual indications of movement described above, the remote reading telltale transponder measures the displacements of the two indicator cylinders electronically. The measurement method is contactless and is designed to meet the demands of the mining environment. The transponders do not use on-board batteries of any kind and are maintenance free. The system has ATEX and MSHA intrinsic safety approvals for Class 1 atmospheres.
The Acoustic Energy Meter is a hand-held, non-destructive testing instrument used to measure the integrity of lined and unlined tunnel surfaces. Its novel measurement technique exploits RMT's specialist experience and field observations in geology and rock mechanics worldwide. Applications to date for the Acoustic Energy Meter include condition surveys of concrete segments and shotcrete tunnel linings and regular safety inspections of gypsum, coal and hard rock mines. The unit comprises an integral microprocessor, geophone and readout unit, with an optional external geophone for high tunnel roofs. Operationally, the meter automatically senses and analyses the complex reverberations which arise when a local tunnel roof, or wall, is struck with a hammer. The associated readout provides a normalised figure of integrity, where:
The Acoustic Energy meter is simple to use. With the meter switched on, the geophone is held against the suspect area with one hand, whilst the local tunnel surface (within 20 cm of the meter) is struck with a hammer. The geophone automatically records, processes and analyses the resulting reverberation impulse and presents a reading and banded LED indication. Interpretation of meter's readings is, by design, readily associated with local conditions. RMT provides appropriate field training and demonstrations can be undertaken on request. The meter has South Africa Ex ib and MSHA intrinsic safety approvals.
CSIRO Hollow Inclusion Cell RMT is the sole UK distributor of Mindata's range of rock stress measurement equipment, including the industry standard CSIRO Hollow Inclusion Cell. This cell conforms to the ISRM standard for in-situ stress management and determines the complete triaxial stress tensor from a single measurement. The CSIRO HI cell is available in 9 or 12 gauge format and standard or thin-walled versions. It is also available with an optional internal precision resistor or a thermistor where temperature compensation is required. This equipment
has an impressive track record for successful stress measurement
by overcoring in weak rock conditions. It can also be used for stress
change monitoring if installed and left in-situ. RMT can also provide
suitable software, adhesive pack sundries, installation and readout
equipment and bi-axial cells for determination of elastic properties
during stress measurement. CSIRO Yoke Gauge The CSIRO Yoke Gauge is a borehole deformation gauge specifically designed for monitoring rock stress changes. Its key features are as follows:
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