Civil Engineering Reference
In-Depth Information
FIGURE 9.38
Subsoil profile, Baosic, Yugoslavia. (
Reproduced from
Ishihara 1985.
)
(horizontal:vertical) slope inclination, and assume that the average level of water in the river
corresponds to the depth of the groundwater table (0.5 m below ground surface). Further
assume that the depth of water in the river is 5 m. Using the “before improvement”
N
val-
ues, will the riverbank experience a flow failure during the design earthquake? If the entire
riverbank and adjacent land are densified such that they have the “after improvement”
N
values, will the riverbank experience a flow failure during the design earthquake?
Answer:
Before-improvement condition: a mass liquefaction flow failure would develop during the
earthquake. After-improvement condition: the riverbank is not susceptible to a flow failure.
9.11
Figure 9.38 shows the subsoil profile at Baosic, Yugoslavia. Assume the site
consists of sloping ground with an inclination of 6 percent. As indicated in Fig. 9.38, the
groundwater table is located 1.5 m below ground surface. The different soil types shown in
Fig. 9.38 have the following properties:
1.
Surface soil:
The surface soil is located from ground surface to a depth of 1 m and has
a total unit weight
t
equal to 18.3 kN/m
3
.
2.
Sand:
The sand layer is located 1 to 6 m below ground surface. The sand has 2 percent
fines. The total unit weight
t
of the sand above the groundwater table is 18.3 kN/m
3
,
and the buoyant unit weight
b
of the sand below the groundwater table is 9.7 kN/m
3
.
3.
Clayey fine sand and silty fine sand:
These two layers are located 6 to 10.5 m below
ground surface. Both soils are not susceptible to liquefaction. Assume that the SPT blow
count at a depth of 6 m is located within the clayey fine sand.
