Mine Design Relating to Mining Direction

Mine Design Relating to Mining Direction:-

This relates mainly to horizontal stress fields. Stress fields are seldom equal in all directions and in a horizontal plane it is usual for there to be a highest stress direction, the "major principal stress",perpendicular to the lowest stress, the "minor principal stress". In general a roadway driven parallel to the direction of the major principal stress will be more stable than at any other angle, the worst direction being perpendicular to the major principal stress.

It may be desirable to lay out the mine such that most of the headings, or at least the main headings are in the best direction and accept that cut-throughs may require heavy support or may be sacrificed at times. Alternatively it may be desirable to mine at an angle in between to get the best conditions possible in both directions.

The effects of stress redistribution on gate roads at the ends of a longwall face and the possible use of goaf areas to "shadow" the gate roads from high stresses is described under the Longwall Strata Control section. This is part of using mine design relating to mining direction to assist in strata control.

Finding best directions may be a case of trial and error in the early stages of a mine's life and there may be other restrictions on using this knowledge (the layout may already be committed by the first area mined, stress fields can change over a lease, other factors may be more important, etc). Where possible however it should be a consideration in mine design.