Goaf Gas Control Improvement by Optimizing the Adjacent Roadway Large-Diameter Boreholes

Figure 2

Diagram of three horizontal and three vertical zones in the goaf and the coordinate system of the proposed model. (A) Collapse zone. (B) Fracture zone. (C) Bending subsidence zone. (a) Natural accumulation area. (b) Load affected zone. (c) Compaction area.