Mechanism and Application of Static Fracturing Technology on Deep Working Face
Table 1
Characteristics of adjoining rock on roof and floor of No. 21209 working face.
Description
Rock name
Thickness (m)
Lithologic characteristic
Upper roof
Fine sandstone
5.5–7.1
Varies greatly in thickness, mainly quartz and feldspar, argillaceous cementation, with wavy bedding, rock Protodyakonov hardness f = 4–6
Immediate roof
Medium sandstone
2–4
Grey to greyish white, dominated by quartz, containing thin layers of micropsammite, argillaceous cement, thin-layered, plate-like bedding, containing plant fossils and mica flakes, rock Protodyakonov hardness f = 6-7
2# coal
Coal
1.0–1.5
Mainly semibright to semidull coal, with thin layers of dull coal, massive structure, developed endogenetic fracture in coal, and containing dirt bands in the lower part of the coal seam
Floor
Micropsammite siltstone
1–7.3
The rock compositions are mainly quartz and feldspar, thin layered, containing plant fossil fragments and mica sheets, horizontal stratification or not showing stratification, the thickness being about 1 to 7.3 meters, and the rock hardness f = 4–6
