Influence of constraint conditions on the seasonal variation of the concrete temperature cracks in a tunnel final lining

Abstract

Temperature and shrinkage cracks are still not rare in tunnel and underground cast-in-place concrete linings. The features of the constraint conditions during temperature dropping stage of the lining in construction are rigorously concerned in terms of crack prevention and magnitude control. The width seasonal variations of the temperature cracks in a tunnel concrete final lining, monitored with vibrating strain gauges, imply that the constraint conditions, on which the temperature and shrinkage cracks developed in the lining concrete during the temperature dropping stage, are working and of successive features in the post-construction period. Therefore, the seasonal variation of the crack widths can partially indicate the constraint conditions of the cast-in-place lining concrete cracking in construction period. Considering the cracks beyond the planned allowable values, the results from this case imply that it is beneficial to apply a flexible layer on the outer surface of cast-in-place concrete lining in concrete crack resistance design and construction quality control, especially for a tunnel with cast-in-place concrete monolithic lining or two-pass lining.