An assessment of coal pillar system stability criteria based on a ...
WEBJan 1, 2017 · The data in Fig. 2, Fig. 3 allow two other very important statements to be made in relation to the stability and hence design of stable coal pillar systems: (1) For w/h ratios of >7, coal pillars are almost certain to workharden as a postfailure behaviour and can, therefore, be classified as "indestructible" ( they retain a confined core at all .