| 摘要 |
PROBLEM TO BE SOLVED: To shorten a construction period by starting work for moving a form 1 for tunnel lining without a delay, when placed lining concrete C is hardened to a state of having predetermined strength. SOLUTION: A protrusion 10 swelling forward is provided on an side end plate 9 for closing the front end surface of a void between the inner wall surface of a tunnel and the form 1 for tunnel lining, so that a concrete portion for determination which integrally continues into the lining concrete C for being placed into the void can be formed in the protrusion 10. The strength of the concrete portion for determination is measured after the placing of the lining concrete C, and the work for moving the form 1 for tunnel lining is started when the strength becomes equal to or exceeds a predetermined reference value. The strength is measured by setting an ultrasonic transmitter and a receiver on opposed surfaces of the concrete portion for determination so as to measure a speed of an elastic wave. COPYRIGHT: (C)2008,JPO&INPIT
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