Stress Distribution and Gas Concentration Evolution during Protective Coal Seam Mining

Figure 4

Vertical stress distribution along retreat direction at various retreat stages. (a) Vertical stress distribution along retreat direction after retreating 40 m. (b) Vertical stress distribution along retreat direction after retreating 80 m. (c) Vertical stress distribution along retreat direction after retreating 120 m. (d) Vertical stress distribution along retreat direction after retreating 200 m.

(a)

(b)

(c)

(d)