A method of sinking a shaft through loose surface deposits by driving a ring of
wood piles down vertically. As the piles are rammed downward, the loose
material is removed. Frames are set to prevent the piles being forced inward.
Each new set of piles reduces the dimensions of the excavation. To avoid this
reduction in size, the piles are driven at an angle away from the shaft space. Nelson
Source:
Dictionary of Mining, Mineral, and Related Terms
