- A case study on piping during excavation for bridge abutments
- T. Tanaka ; E Toyokuni ; E. Ozaki
- Book Title / Journal: Underground Construction in Soft Ground, Fujita & Kusakabe (eds) © 1995 Balkema, Rotterdam. ISBN 90 54 10 536 4
- Year: 1995
- Seepage
- Keywords: bridge abutment ; piping ; excavations
- Description
- This paper, first, reports a case history of piping occurred in a subsoil of a bridge abutment within a cofferdam during dewatering. The countermeasures against the piping are also presented. Second, seepage flow analyses are carried out and stability with respect to seepage failure (i.e., boiling) is investigated. Finally, the causes of the piping are considered, and the following results were then obtained:
At this location, agravel layer is overlaid with a sandy silt layer which has less permeability. In the case of layered
soil of this type, head losses take place dominantly in the upper layer, as a result the large seepage force acts upward
on soil particles. Seepage flow concentrated into the toe of the abutment footing through its construction on the surface of excavation, the seepage velocity became larger and the piping occurred.
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