Excavating near the toe of a dyke
Excavating near the toe of a dyke
(OP)
A 25 ft high dyke sit on top of compact fine sand. The water table at the downstream toe of the dyke is close to the tail water level, ie. the fine sand is almost completely saturated. Removing the sand material beyond the downstream toe of the dyke will cause instability of the dyke. What techniques or methods which can be used to ensure the removal of the sand can be carried out
without jeopardizing the stability of the dyke (want to remove the sand as close as possible from the D/S toe of the dyke). The excavated sandy material may be replaced with rockfill or other fills in the future, if required for long term stability. Excavation may extend to about 20 ft-25 ft deep, which will be in fine sand below water table. Are there techniques where sand can be removed and replaced simultaneously (other than techniques similar to the installation of slurry trench, or stone column placement) ?
PS. Experience in excavation of the sand below water table in the area has been difficult. The sand turned into soupy, flowing consistency. Removing this deposit nearby the dyke, without any shoring or ground improvement techniques may result in catastrophic failure of the dyke.
Would like to hear any ideas from the forum. Thanks.
without jeopardizing the stability of the dyke (want to remove the sand as close as possible from the D/S toe of the dyke). The excavated sandy material may be replaced with rockfill or other fills in the future, if required for long term stability. Excavation may extend to about 20 ft-25 ft deep, which will be in fine sand below water table. Are there techniques where sand can be removed and replaced simultaneously (other than techniques similar to the installation of slurry trench, or stone column placement) ?
PS. Experience in excavation of the sand below water table in the area has been difficult. The sand turned into soupy, flowing consistency. Removing this deposit nearby the dyke, without any shoring or ground improvement techniques may result in catastrophic failure of the dyke.
Would like to hear any ideas from the forum. Thanks.





RE: Excavating near the toe of a dyke
RE: Excavating near the toe of a dyke
RE: Excavating near the toe of a dyke
I think we need a little more information. It would be helpful to know where this project is or at least what 'level' of technique might be availible. Are the restrictions due to lack of equipment or lack of access.
RE: Excavating near the toe of a dyke
You might also try a steel sheet pile along the dyke toe which you could extract as you backfill.
RE: Excavating near the toe of a dyke
RE: Excavating near the toe of a dyke
You should also get an experienced and reputable sheetpiling contractor. This is not a project where the first concern should be the bid price.