For any mining geotechnical study, an understanding of the characteristics of the rock mass within which an underground or open pit mine will be excavated is essential. The condition of the rock mass will determine, for example, the maximum stable stope size that can be formed in an underground mine, the rock support requirements for underground tunnels, the primary fragmentation sizing for a caving mine, or the maximum stable slope angle for an open pit mine. The basis of developing this understanding lies with Rock Mass Classification (RMC). Each RMC system uses sets of discrete input parameters – measures for material strength, discontinuity properties, fracture spacing, number of joint sets, water, stress, adjustments for the excavation environment, etc. - which need to be consistently and unambiguously recorded.
As semi-automated Excel spreadsheets used for the collection, storage and manipulation of RMC data have evolved, SRK has developed a comprehensive geotechnical database management system (GTDMS). The system allows for collecting parametric data for the calculation of four main rock mass classification systems: Bieniawski’s RMR; Laubscher’s MRMR; Laubscher/ Jakubec’s iMRMR and Barton’s Q. It uses MS Excel for data capture and reporting, with MS Access for collation, quality checking, and analysis of the logged data.
The system is fully customisable and can integrate existing data sets. At the start of a project, deposit-specific tables related to attributes such as lithology, alteration, and weathering are created. Project-specific logging codes can also be generated. The RMC’s to be used for the project are selected and fields in the database not required for calculation can be switched off and hidden. This initialisation process generates a customised MS Excel logging sheet containing only the fields and the logging codes (using drop down menus) required for collecting geotechnical data appropriate to that particular project, with built-in quality and error checks. As well as allowing for the collection of core logging interval data, the system also accepts point data into the log from core orientation, geophysical logging, and strength testing. Where core orientation data are present, these are integrated into the interval log to avoid re-counting fracture sets, thus speeding up the logging process.
The system is particularly useful in situations where the client collects the geotechnical data and then provides the database to SRK for interpretation and analysis. SRK will set the system up on site, carrying out customisation and providing training in the use of the system and basic geotechnical logging, if required. The GTDMS has already been used successfully on a number of mining projects. Its primary advantage is the ability to cost-effectively generate a clean geotechnical data set without the need for time consuming error trapping, data validation and verification.
