Reviewing support requirements for existing excavations in underground mines

Tens if not hundreds of kilometres of existing excavations in many underground mines, which were developed many years ago, may not satisfy present geotechnical support requirements. The effectiveness of ground support in mining excavations may be affected by changes to geotechnical and mining conditions. Over time, these changes can lead to ground instability and may result in considerable safety-related problems as well as economic loss. Periodical reviews of support requirements should provide information on the status of ground support in existing underground excavations and on the need for repair or rehabilitation. The geotechnical risk assessment sets out strategies to ensure minimum ground support requirements are met. Where ground stability is affected by deterioration of support or deterioration in ground conditions or support does not comply with current standards, existing excavations should be additionally supported, re-supported or rehabilitated. Some excavations may need periodical scaling or should be barricaded off. To ensure safety of all underground personnel a minimum support standard must be adopted. The approved minimum support requirements may vary depending on size and shape of an excavation, expected service life (stand-up time), usage (often visited or travelled through, storage of material, etc.). Examples of classes of support of various underground excavations are provided. Quality assurance requires that a regular inspection and monitoring programme should be established, carried out by competent persons and conducted for all areas identified during risk assessment.