Abstract:

The safety of open-pit mining in Daxigou Iron Mine is affected by the residual goaf in the

original underground mining.In order to ensure the safety of bench mining in the boundary，four theoretical

calculation methods and numerical simulation are used to determine the safe thickness of the roof in different

span goafs，and the functional relationship between the safe thickness of the roof and the span of the goaf is

established.The goaf in the boundary is classified，and the disposal time is determined in combination with

the safe thickness of the roof of the goaf.The results show that the safety thickness of the roof of the goaf in⁃

creases quadratically with the increase of the span，and the five mined-out areas that have been discovered

in the open-pit mining boundary are all Class I mined-out areas that are simple and easy to deal with.At the

current stage，two goafs should be treated at the elevation of 1 343.9 m. In the future，two goafs should be

treated at the elevation of 1 368 m，and one goaf should be treated at the elevation of 1 356 m，and the treat⁃

ment means are blasting collapse.The research results lay a foundation for the safe disposal of goaf in the

boundary of Daxigou Iron Mine.

Key words:

underground goaf, safety thickness of roof, theoretical calculation, numerical simula?

tion, goaf management