Experimental analysis of seepage flow under coastal dikes

摘要

The effects of both blanket length and sheet pile depth on the seepage rate under coastal dikes was investigated. Laboratory experiments were conducted in a flume 8-m long, 1-m wide, and deep with sidewalls made of a combination of Plexiglas and glass sheets. Perspex walls were used as the body of the coastal dike model, instead of a sloped embankment, and also were employed as the blanket and sheet pile of variable lengths and depths. The sheet pile depth was adjusted at various depths of 10, 20, 30, and 40 cm from the bottom of the flume. The results showed that by considering a sheet pile depth of zero due to boiling and piping of the foundation material, it was not possible to provide a steady-state condition. It has been observed that application of sheet pile alone is not very effective in reduction of seepage or exit hydraulic gradient and therefore, a conjunctive use of impermeable blanket and sheet pile should be considered as the proper measure for controlling piping or boiling phenomena under the coastal dikes or other hydraulic structures.