Abstract: Soil-bentonite (SB) cutoff wall has been widely applied in contaminated soil remediation. Its service performance is largely influenced by stress state and consolidation deformation. Two test sections of soil-bentonite cutoff wall were built for the investigation on the consolidation behavior of SB cutoff walls. The stress state and deformation of the walls were monitored for 15 months using earth pressure load cells, piezometers and inclinometer. Results show that the major consolidation process of SB cutoff wall lasts several months. The dominant form of the wall deformation is lateral deformation. The total stress decreases in the first month, and barely changes thereafter, while the effective stress increases with the dissipation of excess pore pressure. The horizontal strain and the maximum horizontal effective stress are both correlated with the depth of the wall. At the bottom of the wall, both the total stress and pore pressure decrease to the hydrostatic pressure. The effective stress stays low during the major consolidation process. According to the deformation and stress distribution, it is suggested that there may be sliding wedges forming in the adjacent ground, squeezing the backfills integrally, which makes a reasonable explanation of the consolidation behavior of the cutoff walls. At last, recommendations on design and construction of SB cutoff walls have been proposed.

Key words: soil-bentonite, cutoff wall, consolidation, stress state, deformation