Abstract
Preventing concrete spalling is very important in tunnel maintenance because it can be a direct hazard to the operational safety of trains. This paper deals with the applicability of sprayed polyurea as a method to prevent spalling of tunnel linings. Model tests and trials using the method were carried out. According to the model tests, when the arch crown displacement reached 30mm, bending compressive fractures appeared around the shoulder of the lining, no spalling occurred in the lining because the polyurea covered the exfoliated concrete. The model tests therefore confirmed the effectiveness of polyuria application against spalling. For the trials in an actual tunnel, 3 kinds of surface were prepared before application of the polyurea spray, which enabled evaluation of bonding strengths and execution time.
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