ABSTRACT
During mechanized tunneling with a slurry shield in saturated sand, pressured bentonite slurry is often used to counteract soil and water pressures in front of the tunnel face. Due to the pressure difference between the mixing chamber and the ground, the bentonite slurry will penetrate into the sand. This study focuses on the two key processes in bentonite slurry infiltration: mud spurt and filter cake formation. A series of bentonite slurry infiltration tests in saturated sand are presented. The experiments show that the excess pore water pressure will only be present in the sand during mud spurt. After that, the filter cake will form on the sand surface. The distribution of pore water pressure in the sand depends on the bentonite content of the slurry. The differences between the stages of mud spurt and filter cake formation were clearly noticed.
