open timbering

open timbering

[′ō·pən ′tim·bə·riŋ]
(mining engineering)
A method of supporting the ground in a mine shaft or tunnel; supports are several feet apart, with the ground between them secured by struts.

open sheeting, open sheathing, open timbering

open sheeting
Horizontal or vertical planks or boards placed at intervals along the face of an excavation; used where the soil is sufficiently firm to make close sheeting unnecessary and where groundwater is not a problem.