Porosity Distribution Law of Overlying Strata in the Goaf of the Adjacent Working Face: From the Perspective of Section Coal Pillar Types

The porosity distribution law of overlying strata in the goaf has an important guiding role distinguishing hidden disaster-causing factors goaf, such as gas enrichment area and spontaneous combustion area. Existing research is concentrated on a single working face (GSWF), adjacent (GAWF) must be different from that GSWF. By selecting Longshan Coal Mine engineering background applying theoretical analysis, numerical simulation formula-fitting methods, GAWF was obtained for section coal pillar types. results demonstrate (1) according to supporting effect sections widths strata, can divided into three types: with small-section width type (GFST), moderate-section (GFMT), large-section (GFLT). (2) In face, offset distance maximum value each rock stratum middle positively correlated between seam floor. affected by (ASCP), increases increase width, but still smaller than its own initial porosity, rate continuously decreases. (3) From floor upward, spatial form GFST GFMT described follows: partial “dustpan” shape–unilateral “concave-convex peak” combined shape. GFLT shape–“concave-convex shape-“Λ”