Abstract:  The shield tunneling in high water pressure (0.4~0.8 MPa) when crossing the rivers in China is monopolized by imported shield tail sealing grease. Through orthogonal studies, the interaction of the sealing grease′s components is investigated to address this issue. The findings reveal the following: (1) By introducing a thickening rheological agent, the formula creates a lamellar structure with layers spaced 5~10 nm apart, giving base oil and polyisobutylene access space. This allows for the realization of thickening and dispersion, improves the shear rheology of shield tail sealing grease under high water pressure, and ensures the balance between consistency and pumpability. (2) By adding various scales of naturally degradable fibers and other ingredients to the formula, a composite reinforced water resistance structure is created, resulting in 7 MPa water breakdown pressure of highwatertightness pressure sealing grease, which is 1.75 times as much as the imported product. As a result, the reasonable consistency, and pumpability of shield tail sealing grease are achieved, and the water tightness is also significantly improved. It has laid a solid foundation for the further research, development, and transformation of highend shield tail sealing grease for shields in high water pressure and complex strata such as river crossings in China.

Key words: shield tail sealing grease, watertightness under high pressure, pumpability, water breakdown pressure