Slope Stability
Slope Stability
(OP)
Highly saturated area was encountered at the toe while placing engineered controlled fill with a slope of 3:1 to a height of approximately 30 feet. It was noted that the location was a small lake, drained and filled about 50 years ago. According to the observation, the material mainly consists of dark brown fat clay with silt. Also, wetlands and adjacent tributary creek is identified within a previous lake bed (toe area).
Most probably, the above mentioned sub-surface area will be always highly saturated. I appreciate your suggestion to stabilize the ground/or the lake bed area before the placement of controlled fill material.
Most probably, the above mentioned sub-surface area will be always highly saturated. I appreciate your suggestion to stabilize the ground/or the lake bed area before the placement of controlled fill material.





RE: Slope Stability
If safety factors are adequate, you could potentially address seepage by installing a toe drain.
(From reading your original post, I'm not quite sure whether the fill is in place or if you are considering the fill at some point in the future.)
f-d
¡papá gordo ain't no madre flaca!
RE: Slope Stability
At the stated location, the placement of controlled fill is not done, but the developer likes to build the land ASAP. The developer is not interested to engage for further geotechnical explorations. According to the observation, the phreatic surface is at the toe surface level. The wetland and the adjacent tributary creek is very close (wet land -approx. 15'.00 & creek 100'.00 away from the toe/or lake bed) from the toe area. The wet land and the creek is under the core engineering authority and they do not want the developer to disturb the wet land to drain the current stagnant water.
Now without any further field exploration, the developer is looking for a suggestion to stabilize the saturated toe land/or lake bed area before the placement of controlled fill
RE: Slope Stability
Can you go in there with a hand auger and see just how hard/compact the saturated soil are. . ?
f-d
¡papá gordo ain't no madre flaca!
RE: Slope Stability
RE: Slope Stability
What is your opinion to place large rocks (approximately 6-12 inches) into the soft ground after mucking out all highly saturated silty fat clay from the toe area, which will act like geopier to stabilize the soft ground?
RE: Slope Stability
Not sure how large rocks will help. There may be some benefit to a drainage blanket in the form of separation geotextile and open-graded aggregate for subgrade preparation; however.
f-d
¡papá gordo ain't no madre flaca!
RE: Slope Stability
RE: Slope Stability
RCEJD, I appreciate if you could please let me know the location of perventive treatement you applied. Was is at the toe zone? If the preventive treatment was at the toe zone, what was the depth of the treatment?