TM 5-818-1 AFM 88-3, Chap. 7
becomes necessary to construct a field p-e curve
∆H =
simulating consolidation in the field. These constructions
e1 - e2
(5-1)
H
are also shown in figure 3-7. They are based on the
1 + e0
assumption that the straight lower branch of the field p-e
where
curve, K, intersects the laboratory curve at e = 0.4e0.
e1, e2
=
initial and final void ratios,
Furthermore, the field curve must pass through point a,
respectively,
from the field
corresponding to the present overburden pressure and
pressure-void
curves,
the natural void ratio. The field compression index, Cc, is
corresponding to the initial and
taken as the slope of the straight lower branch of K on
final
effective
foundation
the semilogarithmic diagram.
pressures
eo
=
average initial void of the stratum
a. Settlement computations.
The total
H
=
total thickness of the compressible
settlement, ∆H, of a foundation stratum is computed
stratum This formula also may be
used to estimate foundation
according to the following formula:
rebound due to excavation. When
the lower portion of
Figure 5-3. Influence value for vertical stress under a uniformly loaded circular area.
5-7
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