Title:
Tunnel Formwork Removal: When is the Time Right?
Author(s):
Kurt F. Peyfess
Publication:
Concrete International
Volume:
21
Issue:
11
Appears on pages(s):
65-66
Keywords:
compressive strength; form removal; formwork; green concrete; static analysis; tunnel linings
DOI:
Date:
11/1/1999
Abstract:
During the construction of modern large-diameter tunnels, contractors remove the formwork as soon as the concrete is self supporting to meet usually tight schedules. The timing of form removal for conventional one- or two-lane tunnels usually had been left to experience judgment or a rule-of-thumb. These rules were based on the assumed minimum strength which the concrete should have achieved before form stripping. However, material strength alone is never the only criterion for the stability of any structure. Consequently, a complete static analysis of the tunnel lining with the knowledge or at least the reasonable assumption of the parameters for green concrete are necessary to determine the timing of the removal of the formwork.