Abstract: How to prevent shield tail leakage when replacing shield tail brushes is an important and difficult pointduring shield tunnel construction. In this paper, the shield tail brushes were replaced by ‘directly drilling a circle of radioactive holes on the pipe segment’ (scheme 1), ‘shield tail freezing tube and pre-embedded freezing tube segment’ (scheme 2) and ‘setting 2 annular freezing tubes’ (scheme 3), and a numerical model was established to compare and analyze the development law of the temperature field of the frozen soil curtain formed by each scheme. The results show that the frozen soil curtain formed by the three schemes can effectively prevent shield tail leakage, and the volume of the frozen soil curtain formed by scheme 3 is greater than scheme 2 and scheme 1. The sealing time for the gap between the shield tail and the ring is 17 days, 2 days, and 5 days, respectively. The freezing effect at this location of scheme 2 is greater than scheme 3, and the scheme 1 has the worst effect.The improvement measure for scheme 1 is to arrange a radial freezing tube as close as possible to the gap between the shield tails. Scheme 2 and scheme 3 can be adopted in practical engineering,and it is recommended to adopt scheme 3 for freezing reinforcement during the replacement of the shield tail brush.

Key words: replacement of shield tail brush, freezing method, annular freezing, temperature field, numerical simulation