盾尾密封系统是盾构重要系统之一，当其发生故障时，会产生漏水、漏浆等重大施工风险，对盾尾密封系统不同外部水压条件下（2~8 MPa）的密封性能进行深入研究具有重要的现实意义。基于盾尾密封腔的空间构型，结合盾尾密封双向承压实验，运用计算流体动力学方法，对盾尾密封系统进行多相流的数值模拟，研究盾尾刷模型简化方法、盾尾油脂腔压力分布规律和水侵入的流动规律，分析盾尾密封系统不同外部水压条件下的密封性能。模拟结果表明，当注脂稳定后，油脂腔内压力处于0.8 ~1.2 MPa，且油脂腔2压力始终大于油脂腔1压力，其压差始终保持在0.1~0.3 MPa；当水完全击穿盾尾密封系统时，会形成一个稳定的流道；随着水压的不断增加，完全击穿盾尾密封系统的时间逐渐减少，且减少的幅度越来越小。本文针对盾尾密封系统的密封性能所做的流体仿真，可为盾尾密封系统的设计提供理论指导。

Shield tail sealing system is one of the important systems of shield. When it breaks down, it will cause major construction risks such as water leakage and slurry leakage. It is of great practical significance to study the sealing performance of shield tail sealing system under different external water pressure conditions (2~8 MPa). A multiphase flow numerical simulation is performed on shield tail sealing system using computational fluid dynamics method based on the characteristics of space configuration of shield tail seal chamber and the bidirectional pressure experiment. The simplified method of shield tail brush model, the pressure distribution law of shield tail grease chamber, and the flow law of water invasion are studied. The simulation results show that: (1) after the grease injected becomes stable, the pressure in grease chamber is in the range of 0.8~1.2 MPa, and the pressure in grease chamber 2 is always greater than that in chamber 1 with a pressure difference of 0.1~0.3 MPa; (2) when the water completely breaks through the shield tail sealing system, a stable flow channel will be formed; and (3) with the increase of water pressure, the time needed for completely breaking through the shield tail sealing system gradually decreases, and the amplitude reduction gradually decreases. The fluid simulation performed can provide theoretical guidance for the design of the shield tail sealing system.