Objective The water pressure resistance performance of shield tail sealing grease is one of the key factors affecting shield tail sealing capability. A unified and mature standard for its targeted testing, evaluation, and analysis has not yet been formed, necessitating in-depth research.

Method Four kinds of shield tail sealing grease collected from shield construction sites are tested by the Matsumura test device, and the breakthrough time is used as a new indicator to evaluate the water pressure resistance performance of shield tail sealing grease. Through tests, the breakthrough time, breakthrough pressure, grease thickness and wire mesh size of shield tail sealing grease are determined, and a new grading standard for the water pressure resistance capability of shield tail sealing grease is proposed.

Result & Conclusion  The breakthrough time of shield tail sealing grease depends on the formation of the sealing layer, which is jointly determined by the grease type and wire mesh size. The breakthrough time curve of shield tail sealing grease decreases significantly with the increase of water pressure. However, water pressure is not the key factor in grease leakage. Grease thickness is another influencing factor in that insufficient grease thickness fails to form a sealing layer. The water pressure resistance of grease differs between stepwise pressurization and direct pressurization modes. In the breakthrough curve, breakthrough time shows a high negative correlation with pumpability.