ABSTRACT
Subsidence is not only a technical but also a public relations issue. When the public gets involved, surface subsidence provokes a lot of emotion and the mine company usually winds up in court, with an eventual legal solution to problems, while the technical side of the story is of secondary importance. During underground longwall mining, when the gob exceeds a certain size, strata movement reaches the surface and forms a low area of limited size above the gob. This is called the subsidence basin or the movement basin. When the panel width exceeds a critical value, the maximum subsidence reaches its maximum possible value and begins to spread, rather than increases further with increasing panel width. On a major cross-section of the subsidence basin, which is the cross-section at the center of the subsidence basin either along the mining or face line direction, the point dividing the convex and concave portions of the subsidence profile is called the inflection point.
