A box cut is a small open cut created to provide a secure and safe portal as access to a decline

Decline

Decline is a change over time from previously efficient to inefficient organizational functioning, from previously rational to non-rational organizational and individual decision-making, from previously law-abiding to law violating organizational and individual behavior, from previously virtuous to...

 to an underground mine

Mining

Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

. Generally the box cut is sunk until sufficiently unweathered rock is found to permit the development of the decline.
The portal is generally made safe with rock bolt

Rock bolt

A rock bolt is a long anchor bolt, for stabilizing rock excavations, which may be tunnels or rock cuts. It transfers load from the unstable exterior, to the confined interior of the rock mass....

s, wire mesh, and shotcrete

Shotcrete

Shotcrete is concrete conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique....

, which prevents accidental rock falls from closing access to the decline.