Influence of physical characteristics of weak rock mass on height of caved zone over abandoned subsurface coal mines

摘要: This is a study of the height caved zones over abandoned subsurface coal mines in Donetsk, Ukraine. The heights porous weak rock mass shallow, underground workings (up to 80 m) were detected by drilling and linked with laboratory measurements physical characteristics overlying openings. An empirical model developed determine zone workings. shows that decrease uniaxial compressive strength immediate roof increase average porosity layers lead an ratio between It suggested bulking insufficient arrest caving therefore significance formation increased. argued rocks may reach 4.1–11.25 times extraction.