Study on Reasonable Chain Pillar Size in a Thick Coal Seam

Figure 9

Vertical stress diagram of coal pillar during No. 4102 working face mining.

(a) Vertical stress of 0 m advancing the working face

(b) Vertical stress of 40 m advancing the working face

(c) Vertical stress of 80 m advancing the working face

(d) Vertical stress of 120 m advancing the working face