Stress Distribution and Gas Concentration Evolution during Protective Coal Seam Mining

Figure 5

Displacement in the protected coal seam 7₁ at various stages of longwall retreat. (a) Vertical displacement at the roof and floor of protected coal seam 7₁ at various stages of longwall retreat. (b) Tensile displacement in the protected coal seam 7₁ at various stages of longwall retreat.

(a)

(b)