Numerical estimation of pillar strength in coal mines

Results of numerical modelling of failed and stable cases of pillars from Indian coal mines are reported in this paper. The complete procedure for modelling using FLAC^3D in the strain-softening mode is given. It is shown that estimation of pillar strength is possible using numerical modelling and it may provide a viable, and perhaps better, alternative to earlier conventional pillar strength approaches. Methods are given to estimate the large number of input parameters required in the models. Because of the paucity of rock characterisation and in situ stress data, some approximations and assumptions were made in all the cases based on earlier experience. The modelling work leads to the conclusion that such data are necessary for the success of this method. Areas for further research related to this subject are given in the end.