SAFETY FACTOR OF PILLARS
V. UNDUSK
Eesti Põlevkivi Joint Stock Company,
Centre of Applied Researches
10 Jaama St., Jõhvi
EE2045 Tallinn
| This paper deals with the formula for changes in oil shale bed rock durability in Estonian deposit, and discusses possible deviations of rock durability and their probability. It also establishes the dependence of pillars on durability deviation scale, offers their theoretical age and actual safety factor. |