What is the opening rate of shield machines?
In general, composite formations, or hard rock formations, or formations requiring a large number of tools, need to be fitted with a small aperture cutter, usually 10%-35%. Well formed soft soil layer, such as sand layer, clay layer and so on, with large aperture ratio, usually 40%-75%. If the shield involves a change of pressure, it should reduce the opening rate.
The ratio of the area of the cutter opening area to the overall area of the cutter head. The selection of this value concerns the adaptability of the cutterhead to the formation.
Your question is not exact. The opening rate of the shield cutter should be.
