Civil Engineering Reference
In-Depth Information
soil type most susceptible to liquefaction is uniformly graded sand with low fines content.
The grain size distribution curve in Fig. 6.12 indicates a fines content of about 6% and the
soil is clearly a uniformly graded fine to medium sand.
Soil type nos. 6 and 8:
The guidelines for liquefaction susceptible cohesive soil as
indicated in Sec. 6.3 are as follows:
1.
There must be significant earthquake shaking, and the cohesive soil should be non-
cemented and in a loose state.
2.
The cohesive soil should have low plasticity characteristics, such as a plasticity
index less than about seven (PI
7).
3.
The water content should be high relative to the liquid limit, such as a liquidity
index near or greater than one.
There is no information provided on items nos. 1 and 3 above. The only information
available is for item no. 2, the plasticity characteristics. For the eight soils listed in Fig. 6.12,
the soils having the highest plasticity index are soil type nos. 6 and 8. Both of these soils
have a plasticity index equal to 41. Therefore, the soil types least susceptible to lique-
faction are soil type nos. 6 and 8.
6.2
v
58 kPa
20 kPa
78 kPa
v
43 kPa
20 kPa
63 kPa
v
0
a
max
___
v
0
____
CSR
0.65
r
d
g
Eq. (6.6)
78
___
0.65 (0.96)
63
(0.40)
0.31
6.3
CSR
0.65
r
d
v
0
a
max
___
v
0
____
g
Eq. (6.6)
0.65 (0.96) (1.35) (0.10)
0.084
Per Fig. 6.6, for (
N
1
)
60
7.7, intersecting 15 percent fines curve, CRR
0.14
CRR
0.14
_____
_____
FS
CSR
0.084
1.67
6.4
CSR
0.65
r
d
v
0
a
max
___
v
0
____
g
Eq. (6.6)
0.65 (0.96) (1.35) (0.20)
0.17
Per Fig. 6.6, for (
N
1
)
60
7.7, intersecting clean sand curve, and CRR
0.09.
Using magnitude scaling factor (MSF)
1.50 (Table 6.2, 5
1
4
magnitude earthquake) gives
Adjusted CRR
(1.50) (0.09)
0.14
FS
CRR
CSR
0.14
_____
____
0.17
0.82
