Stability of the parting between coal pillar workings in level contiguous seams during depillaring

In India, there are a number of cases of parting failures in mines due to instability of the parting between contiguous seam workings. So far, no suitable norm exists for predicting the stability of the parting during simultaneous depillaring of contiguous seams or sections, the latter being in thick seams. The factors affecting parting stability in contiguous depillaring have been identified as horizontal to vertical in situ stress ratio, width of splits/slices; rock mass rating, parting thickness and combination of different face positions in upper and lower workings. A large number of two- and three-dimensional models were run covering all these variables to arrive at suitable predictive equations to define parting stability and support requirements in contiguous seams/sections during depillaring operations in Indian coal fields. Finally, two representative case studies, briefly discussed in this paper, validated the developed equations for parting stability and support requirements at mine sites.

► Contiguous seams/sections defined in the context of depillaring in Indian Coalfields.
► Stability of parting and associated strata control problems affecting safety and productivity.
► Influencing (ii), six dominating factors identified and parametric study conducted with the help of extensive numerical modelling.
► For (iii), simulated numerical models run to develop formulations and procedure for parting stability and support design.
► Validation at two coal mines with strata monitoring observations presented.