Retention of Failed Strata | Introduction | underground COAL

	STRATA CONTROL
		Retention of Failed Strata

Retention of Failed Strata

If strata fails and the failed material is removed or falls away, in some cases the failure will extend further into the solid. The provision of only a very small degree of confinement can often greatly reduce the extent of the failure.

To a large degree the success of rib bolting in conjunction with a mesh is that only a narrow strip about mid-seam height, can maintain good rib conditions. The immediate rib material may have failed but the support retains the failed material in place and the failure does not extend further.

Where floor heave has occurred, it is often best to leave the broken material in place if the resulting floor conditions are acceptable. The dead load of the failed material will inhibit further deterioration. It is not uncommon that where the failed material is removed, further heave takes place.

Retaining broken material in the roof is less effective because gravity is working against it. It would require the failed material to be pushed back upwards to have any effect.