Geoscience Reference
In-Depth Information
Fig.7.4. Generalizedtestingarrangementstomeasurenonlinearshear-wavepropagation
insituwith adynamically loaded foundation: (a) surfacefoundation and (b) drilledshaft
(fromStokoe et al.,2006)
1.2
Vertical and Horizontal Total Stresses, σ
v
•
σ
h
(kPa)
2
field γ
t
e
46
100
1000
2
4
6
2
field
1.0
V
Svh
before high-amplitude
testing at each static load
V
Svh
after high-amplitude testing
at a static load of 44.6 kN
1000
300
300
lab γ
t
e
900
0.8
lab
800
700
0.6
200
200
600
0.4
Steady-State Testing using Thumpe
r
Geophones 4 and 3
V
Svh
= C
hv
(σ
h
/P
a
•
σ
v
/P
a
)
0.07
C
vh
= 242 m/s or 794 ft/s
500
0.2
From RCTS Testing at an Isotropic
Confining Pressure of 44.1 kPa (6.4 psi)
400
2
4
6
8
2
4
6
8
10
4
10
6
Vertical and Horizontal Total Stresses, σ
v
•
σ
h
(lb
2
/ft
4
)
10
5
0.0
0.0001
0.001
0.01
0.1
Shearing Strain, %
(a) (b)
Fig. 7.5. In-situevaluation of two parameters that affect the dynamic response of soil:
(a)the variation of V
Svh
withincreasing stress (fromStokoe et al., 2005) and
(b) comparison of theG
/
G
max
-log
relationships measured inthe field and laboratory
(fromPark,, 2007)
γ
loads.Ateachstaticverticalload,small-strain,horizontaldynamic loads weregenerated
which permitted vertically propagating and horizontally polarized shear waves
to
be measured. The stress state in the soil is expressed by the vertical and horizontal total
stresses at each measurement depth,
(
S
vh
)
σ
h
, respectively, as discussed by Stokoe and
Santamarina (2000). Clearly, the variation in V
s
with stress state was measured. The log
V
s
-log
σ
v
and
σ
v
· σ
h
relationshiprevealsseveralimportantpointsthatarediscussedinthepre-
sentation (and in Stokoe et al.,2005, 2006).
