Abstract: In this study, comparative evaluation and selection are conducted on various dispersants used in shield tunneling in a clayed stratum. The muck cake disintegration rules under pure water and dispersant are comparatively analyzed, and the disintegration effect of various dispersions and dispersion concentrations on silty clay are investigated. Furthermore, an optimal dispersion is applied to the Yellow rivercrossing tunnel on Jiluo road in Jinan, China. The results indicate the following: (1) Compared with pure water, the dispersants quickly increase the disintegration rate of silty clay, resulting in two variation stages of disintegration rate with time, i.e., rapidly reaches the peak and subsequently reduces due to the reduction of contact face area between the dispersant and water. (2) The total disintegration time decreases with an increase in the dispersant concentration. The disintegration effect of the dispersant is maximum only when the dispersant concentration reaches a certain value. (3) An optimal dispersant B with the best disintegration effect and low cost is chosen and applied to a project. The applicable results show that the shield tunnel speed is improved, and the tunnel parameters become more stable, verifying the rationality of the test data.

Key words: slurry shield, muck cake dispersion, silty clay; dispersant, soil conditioning, disintegration