Experimental study on grouting repair of tunnel lining concrete with non‐through cracks and its safety variation patterns

In order to investigate the compressive characteristics and safety variation patterns of tunnel lining concrete with non‐through cracks in sulfate environments after grouting repair, a field investigation was conducted. Based on the evaporative corrosion characteristics of tunnel lining, a 270‐day grouting experiment with non‐through cracked concrete was designed. Uniaxial compression tests and acoustic emission (AE) tests were conducted to explore the effect of crack grouting on tunnel safety. The results show that: (1) The corrosion sites were primarily concentrated on the sidewalls and sidewall feet. (2) Crack grouting improves the immediate strength of the lining; however, the effectiveness of grouting decreased with time, and after 270 days, it showed no significant improvement. (3) During uniaxial compression, the AE stages I–IV corresponded well to the compaction, elastic, yield, and post‐peak stages of the stress–strain curve. (4) After crack grouting, the yield point of the specimens under compression was delayed; the proportion of AE stage II decreased, while that of stage III increased. (5) Crack grouting did not alter the failure characteristics or AE properties of the non‐through cracked concrete specimens during compression. (6) With increased operational time, the grouting efficiency for sidewalls decreased, while that for sidewall feet increased.