Environmental Engineering Reference
In-Depth Information
East Rutherford, N. J.
(EI.
Depth
m
N
3 ft MSL)
Meadowmat and
organic silt
Dark gray silty
fine sand
+
ft
1
9
Firm gray silt
and clay, 1/8-in
varves, lenses
fine sand
20
5
10
5
LL = 34 (CL)
PL = 22
w
n
= 34
40
3
- becoming soft
LL = 50 (CL)
PL = 28
w
n
= 50
2
60
3
- becoming red-
brown with 1/2 in
varves
20
3
80
5
- 1 in. varves
7
100
30
10
Red-brown silty
fine sand
18
120
25
50
180
33
FIGURE 7.97
Log of test boring (Glacial Lake Hackensack, East Rutherford, New
Jersey) (see
Figure 7.93)
.
(Courtesy of Joseph S. Ward and
Associates.)
Glacial till
Shale rock
60
200
27 years. Center settlements of buildings from 20 to 21 stories high totaled from 0.8 to 3.8
in. (20-96 mm) and maximum differential settlement between center and corner was about
1.5 in. (40 mm). Generally, between 75 and 85% of primary consolidation occurred during
construction, attesting to the rapid drainage characteristics of the varved clays.
Strength vs. Overconsolidation Ratio (OCR):
In general, glacial lakebed clays have low
activity and low sensitivity. Some data on the strength and sensitivity of varved clays from
a number of U.S. cities are given in
Table 3.38.
The shear strength characteristics of varved
clays from the New Jersey-Hudson Valley areas are presented by Murphy et al. (1975) in
terms of the undrained strength-effective stress ratio (
s
u
/
σ
v
) vs. the OCR, and are given in
Figure 7.100.
The high degree of overconsolidation characteristic of these soils is apparent.
The limits of the varved clays from the Connecticut River Valley as presented by Ladd and
Wissa (1970) are also shown. Although these formations are 120 mi apart, their postglacial
depositional histories are similar as are their general engineering properties. The primary
differences are the thicknesses of the silt and clay varves from location to location.
