Mining in Manitoba

Caving Method


Caving Methods


Sublevel Caving

Return to Underground Mining Menu


Engineering considerations

Geology :



Other :

Two factors play important roles in induced caving. One is the occurrence of intersecting joints and shears in the orebody. The second factor is the size and extent of the undercut. The thickness of the slices that break away correspond closely to the width of the stoping area below from which ore will be withdrawn.

The process of planned undercutting starts in the upper area of a block with the driving of drill drifts in ore along the footwall contact, over the line of boxholes. Starting from one drill drift, a slot raise is driven up the contact in ore, passing through the several drill drifts above. Parallel holes are drilled into the back of this raise and blasted, to enlarge the raise to a rectangular height of 20 feet, normal to the footwall. This enlarged slot raise, which is the initial phase of the undercutting, is extended laterally by long-hole drilling and blasting in radial patterns from each respective drill drift, the broken ore being drawn as necessary to provide space for further breaking.

Eventually the widening of the undercut starts the desired caving of the ore above. Usually, a width of about 50 to 100 feet along the strike must be undercut for a distance of about 800 feet down the dip to induce caving. In the caving action fragmentation occurs, a fair amount of the caved material breaking into smaller pieces, small enough to be handled in the drawpoints. Considerable blasting of blocks of ore must be done at the boxholes.