When considering blast designs, another option is the fan cut, which is an angled cut that is similar to half a V-Cut. It is called a fan cut because it looks like an open hand fan from the last century and before, as illustrated in Figure 1. These holes operate on the principle that breaking rock with the face parallel to the blast hole (in a fashion similar to bench blasting) is one of the most optimal and easiest methods of breakage.
The fan cut allows for relief to quickly and easily be made as the hole angles are quickly transitioned into straight in holes. Because of the geometry, smaller drifts can be mined with a fan cut because a drill can be set up in the middle or far side of the round and the fan portion of the cut can be placed on the opposite edge of the face.
Available at: http://works.bepress.com/paul-worsey/64/