ABSTRACT
This collapse may initiate as strata begun to delaminate due to tensile splitting along bedding or lamination planes (Diederichs & Kaiser, 1999). These strata then sag into the excavation.
Ultimately this would result in brittle failure of the roof strata which would collapse into the mine working resulting in the upwards migration of the void. This migration will continue to the surface unless halted by natural arching, choking of the void by collapse debris or by the presence of a high strata within the rock mass above the void. If the void reaches the surface, a crown hole will form.
