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[Q]: Seismic bearing capacity of dense saturated sand ...

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Hi,

The problem I have is concerning the seismic design of shallow
foundations under following conditions:

1. thick layer of very dense sand,
2. ground water table as high as the ground surface
3. very high seismic loading, ca. 0.4 g
4. foundation size, ca. 10 x 10 m

************ What I know:

Since the soil is dense, I think it may not be susceptible to
liquefaction and liquefaction calculation is not necessary.

However, the EQ waves will develop inertia forces within the soil volume,
which will be equilibrated by dynamic stresses (mainly horizontal shear
stresses).
These stresses mobilize a fraction of the available soil strength and
consequently the strength available to balance the inertia forces arising
from the superstructure
is not necessarily the full soil strength. As an extreme case, when the
ground acceleration,
at a given depth, is too high, the induced seismic stresses are limited by
the soil strength
(called dynamic fluidization).
Hence, for very high ground accelerations, no equilibrium can be reached,
even in the absence
of a foundation ! 

*********************What I do not know:

I cannot find any word in the codes about this problem !

In this regard, what is the seismic design calculation procedure for shallow
foundations on saturated dense sand
according to the most recent US codes ?

Could you recommend some publications ?

I would be very thankful to you if you could help me with some information.

Best regards,
Peter Rangelow
Frankfurt, Germany