Falling pieces of tunnel lining hitting a train could cause an accident. Regular tunnel maintenance to prevent this is therefore essential. Repairs are planned and carried out in areas where there is a potential risk of spalling. A method called the “polyurea resin spraying method,” has been developed to prevent spalling by spraying tunnel linings with polyurea resin. This paper presents the results of a study carried out to extend the applicability of this method and some application examples: the effect of surface moisture during application on the adhesion strength of the resin, long-term durability in the presence of leaking water, adhesion strength of the resin on an uneven surface, and results of its application in a real tunnel.
YASHIRO et al. (Sun,) studied this question.