Environmental Engineering Reference
In-Depth Information
STEPHEN FISTER
HOUSES
JAMES WELDON
JOHNSON HOUSES
ROBERT H. TAFT
HOUSES
JEFFERSON HOUSES THOMAS JEFFERSON PARK
20
+
+
20
0
0
50
50
ROCK
ROCK
100
100
150
150
FIGURE 7.98
Geologic section across mid-Manhattan at 113th Street. (From Parsons, J. D., Proc. ASCE J. Geotech. Eng. Div .
102, 605-638, 1976. With permission.)
TABLE 7.13
Typical Properties of New York City Varved Clays a
Characteristic
Clay Varves
Silt Varves
Constituents
Gray clay 10 to 22% of deposit
Red-brown silt: 40 to 80% of
LL
62%, PL
28%, W
46%
deposit
D 10
28%
Gray fine sand: 50 to 40% of
deposit
D 10
0.017 mm, W
0.03 mm, D 80
0.15 mm
Consolidation Preconsolidation
8-13 kg/cm 2
Overconsolidation ratio
3-6
Void ratios
1.2-1.3
0.7-0.85
Void ratio vs. pressure
See Figure 3.81d
See Figure 3.81j
Recompression indices
0.1-0.2
0.15-0.04
Coefficient of consolidation C v
0.05 ft 2 /day (0.005 m 2 /day)
1.0 ft 2 /day (0.09 m 2 /day)
(vertical, inrecompression)
Coefficient of secondary
0.3% strain/time cycle
0.1% strain/time cycle
compression
Shear strength
From undrained triaxial tests: 1-1.5 tsf
From field vane shear test: 1.25-1.75 tsf
a
After Parsons, J.D., Proc. ASCE, J. Geotech. Eng. Div ., 102, 605-638, 1976.
7.6.5
Glacial-Marine Clays
Origin
Clays from glacial runoff were deposited in marine estuaries along coastlines and subse-
quently uplifted to become land areas by isostasy (rebound from removal of the ice load).
Geographic Distribution
Sensitive marine clays are found in the St. Lawrence and Champlain lowlands of Canada,
along the southern Alaskan coastline (see Section 9.2.11), and throughout Scandinavia. The
“blue clay” underlying Boston, Massachnsetts, has relatively low sensitivity compared
with other glacio-marine clays.
 
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