Proceedings of the Deep Mixing 2015 Conference, (DFI)
Deep Mixing Column Group Reinforcement by a Shallow Mixing Layer beneath an Embankment
Binh T. T. Nguyen, Tokyo Institute of Technology, Japan; Tomohide Takeyama, Tokyo Institute of Technology, Japan; Masaki Kitazume, Tokyo Institute of Technology, Japan
Deep mixing columns are widely used to support embankments constructed on soft ground area. Researches on the stability of deep mixing columns were done by some authors when the columns do not simultaneously fail but individually fail at different time. A layer of shallow mixing is proposed to reinforce these columns as a group to increase the stability as well as loading capacity of columned improved area. Two centrifuge model tests were done to observe the effect of shallow layer on reducing embankment displacement as well as on failure pressure of improved ground. Acrylic piles were used as deep mixing columns in the centrifuge tests to avoid unexpected internal failure of columns. The results of centrifuge tests were also simulated by 2D FEM to back-analyze the centrifuge experiments. A good agreement between the centrifuge experiments and the numerical simulations shows that by using a shallow layer reinforcing individual columns, the horizontal displacement at the embankment toe reduces by 60 % and the tilting failure is clearly indicated in columns without shallow layer. Although, no significant failure was observed under the current centrifuge condition, the failure pressure of improved ground was significantly increased with the columns reinforced by shallow layer.
|article #2091; publication #1013 (DM-2015)|