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Preloading and Surcharge
- Thread starter geomane
- Start date
I do not have that textbook
I do recommend Embankments on Soft Clay by Leroueil.
or Design and Performance of Embankments on Very soft soils.
From my experience estimating preloading settlement uses the same principals as footing settlements requiring the void ratio and the coefficient of consolidation be determined for the e log sigma method. In irregular geometry jobs I use finite element modelling with Sigma/W by Geostudio using the cam clay model.
The first stage of site investigation is desktop and it informs the engineer of the anticipated subsurface conditions. By precluding the site investigation the design engineer cannot accept any responsibility for providing a safe and economical design.
I do recommend Embankments on Soft Clay by Leroueil.
or Design and Performance of Embankments on Very soft soils.
From my experience estimating preloading settlement uses the same principals as footing settlements requiring the void ratio and the coefficient of consolidation be determined for the e log sigma method. In irregular geometry jobs I use finite element modelling with Sigma/W by Geostudio using the cam clay model.
The first stage of site investigation is desktop and it informs the engineer of the anticipated subsurface conditions. By precluding the site investigation the design engineer cannot accept any responsibility for providing a safe and economical design.
Here's what I found:
f-d
ípapß gordo ainÆt no madre flaca!
f-d
ípapß gordo ainÆt no madre flaca!
- Thread starter
- #4
Dear jmcc3265,
Not to be glib in my response. I've designed many projects with consolidation. Mitigated it using wick drains, surcharges, etc. At the core of all this are our first principals. That's what I go by - nothing more and nothing less.
You should have Cv, Cc, Cr, e-naught, gammaB, gammaS, P-naught, etc for each layer/sublayer that will consolidate. You should have loads and the attenuation of those loads with depth. You should already have figured out to what depth the delta sigmaH is less than 10 percent of the overburden load and know your, "Seat of Settlement."
In that light, you now have all your boundary conditions. Now you just have to adapt these boundary conditions to the expect5ations of the client. If the client expects ground improvement in 2 months and when their new loads are applied the latent settlement is less than 1 or 2 inches, then you have everything needed to run the numbers. Wicks on 2-ft centers? Wicks on 5-ft centers? No wicks at all? 5-ft preload? For how long? What do you expect for the excess pore pressures when the preload is removed? These are all topics addressed by Terzhagi and others.
This is the fun stuff!
f-d
ípapß gordo ainÆt no madre flaca!
Not to be glib in my response. I've designed many projects with consolidation. Mitigated it using wick drains, surcharges, etc. At the core of all this are our first principals. That's what I go by - nothing more and nothing less.
You should have Cv, Cc, Cr, e-naught, gammaB, gammaS, P-naught, etc for each layer/sublayer that will consolidate. You should have loads and the attenuation of those loads with depth. You should already have figured out to what depth the delta sigmaH is less than 10 percent of the overburden load and know your, "Seat of Settlement."
In that light, you now have all your boundary conditions. Now you just have to adapt these boundary conditions to the expect5ations of the client. If the client expects ground improvement in 2 months and when their new loads are applied the latent settlement is less than 1 or 2 inches, then you have everything needed to run the numbers. Wicks on 2-ft centers? Wicks on 5-ft centers? No wicks at all? 5-ft preload? For how long? What do you expect for the excess pore pressures when the preload is removed? These are all topics addressed by Terzhagi and others.
This is the fun stuff!
f-d
ípapß gordo ainÆt no madre flaca!
howardoark
Geotechnical
You also need to have some understanding of the horizontal hydraulic conductivity. I convinced a client they needed wick drains and got 8 inches of settlement in about a week. I think they still needed the wick drains, but we could have spaced them further apart.
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