Goaf Site Stability Detection in the Overlap Area of Coal Mining Subsidence and Urban Construction

Table 4

Evaluation criteria for site stability of goaf by longwall mining based on surface subsidence observation values.

Stability levels	Surface subsidence (mm)
	1 month	3 months	6 months	12 months
Stable	≤5	≤15	≤30	≤60
Basically stable	5–10	15–30	30–60	60–120
Understable	10–30	30–60	60–120	120–240
Unstable	≥30	≥60	≥120	≥240