Infiltration behaviour into sand of bentonite slurry with guar gum

Bentonite slurry is widely used in various projects due to its excellent engineering properties. The behaviour of slurry infiltration, especially filter cake formation, is directly related to the effect of slurry. This paper proposes an improved apparatus to investigate the infiltration of a novel bentonite slurry, especially in the dynamic infiltration process of the slurry-driven shield, which provides significant references for tunnel excavation. According to monitoring indicators of water discharge volume, pore-water pressure and electrical conductivity, the hydraulic conductivity of filter cake and the major zone of infiltration were analysed. Besides, the results of scanning electron microscopy reveal the micro-interaction between slurry and the soil. The results illustrate that the bentonite slurry with guar gum could immediately form an external filter cake with an infiltrated zone. The external filter cake formed again with a denser bentonite clay platelet network after excavation in the condition of relatively short excavation distance. Therefore, this kind of slurry could rapidly stabilise the excavation surface in slurry-driven shield tunnelling.