Theoretical Calculation Method of Open-Loop Pressure for Sleeve-Valve Pipe Grouting and Engineering Verification

The sleeve-valve pipe grouting technique is widely used in railway, highway, and house construction in China for its outstanding advantages in recent years. However, as the key parameter of sleeve-valve pipe grouting, the open-loop pressure of sleeve body material is still mainly determined by engineering experience. A sophisticated and reliable calculation theory and method have not been established. The role of sleeve body material used in sleeve-valve pipe grouting and the transformation of the acted object by the slurry pressure during the grouting process were systematically analyzed. The stress calculation method of the soil layer around the slurry outlet of the sleeve valve pipe in any inclined state and sleeve body material was obtained. Then, the open-loop failure condition of sleeve body material was proposed, and finally, the theoretical calculation method of open-loop pressure for sleeve-valve pipe grouting, considering the comprehensive influence of multiple factors, was established. Based on these calculation methods, the influence law of some factors of the open-loop pressure was studied deeply, and it was found that the open-loop pressure increases with the increase of the strength of sleeve body material, the elastic modulus ratio of sleeve body material to grouted soil, and the depth of grouting and decreases with the increase of the ratio concerning with Poisson's ratio of sleeve body material and grouted soil. The orientation (characterized by α and β) of the grouting hole in sleeve-valve pipe grouting has a noticeable effect on the open-loop pressure. When α is constant, the open-loop pressure increases obviously with the growth of β, and when β is constant, the open-loop pressure increases with the increase of α. Taking the DK107 + 105 frame jacking culvert project of the newly built Daye North–Yangxin railway as an example, the theoretical calculation method of open-loop pressure established in this paper was applied and verified. The calculated results showed that the outcomes calculated by using the method proposed in this paper are more consistent with the measured values of open-loop pressure at the engineering site and are better than the values of open-loop pressure calculated by these existing methods. The research results can support the development and improvement of sleeve-valve pipe grouting theory.