Single Rectangular Chain Pillars

Rectangular chain pillars are employed extensively and frequently in preference to square pillars in view of less junctions being formed during development. The average pillar stress is given by:

for w/h < 2 tan f

for w/h >= 2 tan f

Where :

w = width of longwall face (m)
h = depth below surface (m)
g = average density of overburden (kg/m3)
f = average angle of shear (o)
p = pillar width (m)
L = pillar length (m)
B = bord (heading) width (m)

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