An observational approach for assessment of dynamic loading during underground coal pillar extraction

On the basis of a large number of field investigations, in and around underground coal mining faces (bord and pillar) in India, this paper discusses issues of measurement and analysis of strata control parameters. Requirement of different types of instruments along with their suitability to monitor the strata control parameters under varying geo-mining conditions of the existing coal mines is also briefly explained. On the basis of field experiences, it is observed that the type of instrument to be placed in and around a depillaring face is more or less dependent upon the geo-mining conditions of the site. Field investigations showed that the continuous monitoring (in time) of these instruments, preferably with the help of a data-logger, can provide important information about performance of mining structures (bord and pillar) during caving of a competent overlying roof stratum. However, in absence of a data-logger, a simple process: called as Combined-Instruments-Approach (CIA) is implemented for some improvement in visualization of overlying strata behavior through manually observed data of the instruments. Scope of application of this approach to anticipate caving behavior of strong and massive roof strata during conventional depillaring practice is demonstrated through analysis of an actual field monitoring results.

► A review of the strata monitoring, with special reference to Indian practices for bord-pillar mines, is presented.
► Influence of existing geo-mining conditions over the field monitoring plan is briefly explained.
► A simple concept of Combined-Instruments-Approach (CIA) is introduced to analyze manual monitoring data.
► Scope of application of CIA is demonstrated to visualize roof strata behavior during conventional depillaring practices.