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Safety and health in mines research advisory board
Annual review 2006


Ground control

Geotechnical classification, modelling and exploitation for safe and efficient mine layout and tunnel support design

Practical work by Rock Mechanics Technology Ltd (RMT), UK Coal Mining Ltd and the University of Nottingham on this RFCS collaborative project, RFC CR 03011, was completed in August 2006.  Since then, RMT, as Project Co-ordinator, has been preparing the final report, which will include the contributions of all the other European Partners.

The Project has mainly involved development of numerical modelling tools for improved mine layout and support design, particularly 3D modelling of strain softening rock behaviour. The work included considerable rock testing, incorporation of the rock testing results into modelling techniques and improved scaling of laboratory test results to in-situ conditions.  RMT’s work has concentrated on developing new three dimensional modelling techniques to solve practical problems of mine layout and support design and improved modelling of goaf and abutment stresses.  UK Coal has provided access to underground sites and other practical assistance.

Particular examples of the application of these techniques during the Project by RMT have included:

Development of more innovative support systems for gateroads under the influence of rock stress

This three year RFCS project, CT-2005-00002, has just passed its half way stage. RMT’s main activities under the Project are:

An important issue regarding coal mine geotechnical instrumentation, which is being addressed under the Project, is the obsolescence of two of the main instruments currently in daily use for monitoring rockbolting roadways, namely the Sonic Probe Extensometer and Strain Gauged Rockbolt Readout. Both have been discontinued by the manufacturer, Soil Instruments, and all stocks have been depleted. No alternatives were available on the world market.

Progress to date is summarised below:

Properties of flexible strand rockbolts and long tendons

HSL’s Metallurgy & Materials section was asked by HSE to characterise the mechanical and metallurgical properties of stranded rockbolts and long tendons as a contribution to the revision of the British Standard for rock reinforcement in mines.  A wide range of different stranded rockbolts and tendons are used by the deep mining industry. These can be used with polyester or cementitious grouts.  The purpose of this work was to establish base line mechanical properties and testing methods for different types of rockbolt and grout for incorporation into the British Standard.  The work has shown that it is difficult to standardise a method for tensile testing because the results are affected by failure at the rockbolt / grout interface.  This stage of the work is complete.

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Updated 2009-05-22