Environmental Engineering Reference
In-Depth Information
FIGURE 3.63
The flat dilatometer. (From Manchetti, S. et al.,
IN SITU 2001,
International Conference on In Situ Measurement of Soil Properties,
Bali,
Indonesia, 2001. With permission.)
where
σ
vo
is the overburden stress and
u
0
the pore pressure, both preinsertion.
I
D
(
p
0
p
1
)/ (
p
0
u
0
) (material index)
(3.53)
Estimating
φ
The friction angle
φ
safeDMT
28
o
14.6
o
log
K
D
- 2.1
o
log
2
K
D
(3.54)
Estimating s
u
(c
u
)
The undrained shear strength
c
uDMT
0.22
σ
v0
(0.5
K
D
)
1.25
(3.55)
See Manchetti (1980), Totani et al. (2001), and Manchetti et al. (2001).
Pressuremeter
The pressuremeter is used to estimate the undrained shear strength (see
Section 3.5.4)
.
California Bearing Ratio (CBR) Test
Purpose
A penetration test is performed to determine the California bearing ratio (CBR) value for
base, subbase, and subgrade materials upon which pavement design thicknesses are based.
Laboratory Test Procedure (ASTM D1883)
A series of specimens are compacted in 6-in.-diameter molds to bracket either the standard
or modified optimum moisture (see
Section 3.2.3)
.
A surcharge weight is placed on the soil
surface and the specimens immersed in a water tank for 4 days to permit saturation while
swelling is measured. A mold is placed in the testing apparatus
(Figure 3.64)
a
nd a plunger
1.91 in. in diameter is forced to a penetration of 0.1 to 0.2 in. (penetrations to 0.5 in. are
