The Effectiveness of Sidewall Softening in Maintaining Mine Roadway

Fundamental study on roadway closure (4th Report)

Abstract

Sidewall softening technique is based on the transference of the high stress concentration further away from the roadway sides. This technique is accomplished by softening the parts of sidewalls of mine roadway by drilling holes, explosions or cutting slots into the sidewalls.
The effectiveness of sidewall softening in maintaining mine roadway is studied using finite element analyses and model tests. The results obtained in this study are as follows.
(1) Sidewall softening improves the stress states around mine roadway. But it must be noted that under certain geological or ground pressure conditions softening would produce the tensile stresses in the roof or floor of the roadway.
(2) Floor lift and side closure could be controlled effectively by sidewall softening, especially when the roadway has a weak fl oor.
(3) Good results of controlling floor lift could be obtained by softening the large parts of sidewalls.
(4) Main failures which occur in the vicinity of the top of softened parts are accompanied by large roof lowering without roof falls. So, in practice, one should take necessary steps to control the roof lowering.