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18
If one side of the cell lies in contact with a rigid structure, e.g., a concrete retaining wall or a
concrete bridge footing, then:
2
Y = 0.73 PR (1-ν
) x 0.5/E = 0.36 PR (1-ν
And
2
P (D/G + 0.36 R (1-ν
Where (E) pertains to the soil material.
Since these expressions are only approximate, they can be simplified even further:
6
For all E < 10 x 10
psi the term D/G is negligible, so long as the cell is designed and constructed
properly, i.e., G is large, (no air trapped inside the cell), and D is small. In addition, the term (1-
2
ν
) can be replaced by 0.91 since ν usually lies between 0.25 and 0.35.
The total embedment is given by:
And for contact pressure cells:
Some typical values of the various parameters are:
50/50 Glycol/Water
Embedment Material
Compacted Ottawa
Weathered Rock
2
)/E) = KD
P = 1.5 EKD/R
Equation 12 - Total Embedment
P = 3 EKD/R
Equation 13 - Total Embedment for Contact Pressure Cells
Liquid
Oil
Mercury
Water
Glycol
Plastic Clay
Soil
0.001 to 0.02 [Ref 2]
Sand
Sand
Concrete
Table 3 - Typical Values of Various Cell Parameters
)/E
psi /
o
C
psi /
o
C
K x 10
-6
/ ºC
700
180
170
650
400
E x 10
psi
6
0.003
0.02 to 0.06 [Ref 3]
0.2
0.04 to 0.11 [Ref 4]
5.0
G x 10
6
psi
0.3
3.6
0.3
0.26
0.28
ν
0.25 to 0.45
0.28 to 0.35
0.25
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