Settlment characteristics of deep engineered fill
Settlment characteristics of deep engineered fill
(OP)
Can anyone assist me with information of the settlement of engineered fill. the fill is a minimum of 4 m thick and has been well compacted throughout to become stiff to very stiff in consistency.
S McCormack
S McCormack





RE: Settlment characteristics of deep engineered fill
Settlements will largely depend on
a) the magnitude of the applied pressure
b) the size, shape and type of the foundation
c) the preconsolidation pressure of the soil layer(s)
d) the thickness of the soil layer(s)
e) the initial void ratio of the layer(s)
f) the shear strength of the soil layer(s)
You will need to determine/estimate the void ratio, and preconsolidation pressure. You can estimate these from determinations of the unconfined compressive strength/undrained shear strength, in-situ moisture content and Atterberg limits.
You will then need to compute the settlements using these parameters. Most geotechnical textbooks can show you how to do this. I prefer to discretize the soil profile into layers corresponding to the soil sampling interval and sum the individual results, after computing the change in stress due to the applied load for each layer.
Be careful that the applied stress does not extend below the zone of engineered fill into a relatively weak soil.
If you have any more specific information, please share it and we can give more particular advice.
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
www.ttlassoc.com
RE: Settlment characteristics of deep engineered fill
RE: Settlment characteristics of deep engineered fill
I have requyested atterberg tests and moisture contents and the consistency was assessed using pocket penotrometer and dynamic cone penetrometer to 5 m. Below the controlled fill is a stiff natural clay layer which in turn is underlain by shale bedrock at approx 8m. The structure proposed to be constructed is relatively light requiring an allow. bearing pressure of 150 kPA which should be adequate.
How would i estimate void ratio and preconsolidated pressure
RE: Settlment characteristics of deep engineered fill
RE: Settlment characteristics of deep engineered fill
Assuming that the fill was monitored during placement and compacted to at least 95 percent standard or 90 percent modified Proctor, I would not be the least bit concerned about the self weight settlement of 4 meters of fill.
If you don't know what the compactive effort was, then you have a big problem and need to do borings and/or test pits to evaluate the fill.
RE: Settlment characteristics of deep engineered fill
RE: Settlment characteristics of deep engineered fill
The salient point to be studied, in my view, is whether or not the "stiff to very stiff fill" is in any way problematic. I guess that where I have/do practice, we don't number crunch as much as others might for the situation as described - our experience and judgment is important. (I know, all, go ahead and hit the bulls-eye on this last statement!)