Earthquakes - Geotechnical Engineering Investigation - page 947

Hydrometer analysis
Grain size in mm.

Sieve analysis
Number of mesh per inch, U.S. standard

Size of opening in inches

100 0

Envelope of 19 curves of
sands that liquefied during
earthquakes in Japan.
Kishide (1970)

80 20

Sands at niigata in
15 to 30 feet depth
range. Seed and
Idriss (1967)

60 40

40 60

Most liquefiable soils
based on laboratory tests.
Lee and Fitton (1968)

20 80

1964 Alaska
Earthquake

0 100

Grain size in millimeters

Coarse Fine Coarse Medium Fine

Cobbles Finer

Gravel Sand

FIGURE 11.34
Effect of grain size distribution on liquefaction susceptibility (cyclic mobility). (After Shannon and Wilson, Inc.
and Agbabian-Jacobsen Associates, 1971; from Finn, W.D., Proceedings of the International Conference on
Microzonation, Seattle, Vol. I, November 1972, pp. 87-112. With permission.)

and 0.25 mm, and the uniformity coefficient (see Section 3.2.3) is between 2 and 10. In gen-
eral, the liquefiable soils had SPT N values 25. Zeevaert (1972) considers that under cer-

tain conditions soft to medium clays undergo a partial liquefaction, although they do not
become fluid on level ground. Many types of clays and clayey silts are susceptible to liq-
uefaction on slopes as discussed in Section 11.3.4.
Nonsusceptible soils : Gravels and sandy gravels, regardless of N values (Seed, 1975), and
stiff to hard clays or compact sands, regardless of being situated on level ground or in
slopes, appear to be nonsusceptible to liquefaction.

<

Foundation Damage Susceptibility
Case Study: Niigata, Japan (Seed, 1975)
General : During the earthquake in Niigata, Japan, in 1964, liquefaction caused a great
amount of damage but distribution was random. The city is underlain by sands up to
depths of 30 m. Gradation is characterized generally by a 10% size ranging from about 0.07
to 0.25, with a uniformity coefficient between 2 and 5 (uniformly or poorly graded).
Damage zoning : Three zones were established relating damage to soil conditions:

Zone A : Coastal dune area with dense granular soils and a relatively deep water
table experienced very little damage to structures.

●

Zone B : Relatively old alluvium of medium-compact to loose sands with a high
groundwater table experienced relatively light damage to structures.

●