Coal pillar loading in shallow mining conditions

Monitoring of the nature and amount of mining-induced stresses over pillars was undertaken at different coal seams with shallow depth cover and varying overlying strata and goaf treatment. The development of abutment loading on the coal pillars facing goaf line is visualised by analysis of the in situ observations at different sites with varying geomining conditions. The rock properties and depositional conditions of the immediate roof strata at each site were studied and incorporated in terms of a cavability index. Considering the relevant geomining parameters, which influenced the pillar loading, empirical relations are developed to estimate the range of influence and the value of ultimate induced stress (vertical) over the coal pillars with shallow depth cover.