Environmental Engineering Reference
In-Depth Information
TABLE 3.29
Values of Compression Modulus E c and Ultimate Pressure P L from Menard Pressuremeter Testing a
Soil Type
E c (tsf)
P L (tsf)
Peat and very soft clays
2-15
0.2-1.5
Soft clays
5-30
0.5-3.0
Firm clays
30-80
3.0-8.0
Stiff clays
80-400
6-25
Loose silty sands
5-20
1-5
Silts
20-100
2-15
Sands and gravels
80-400
12-50
Till
75-400
10-50
Recent fill
5-50
0.5-3
Ancient fill
40-150
4.0-10
Glacial till (Ohio)
600-1500
Ward (1972)
Residual soil (schist)
20-160
Ward (1972)
Decomposed schist
200-500
Ward (1972)
Residual soils (schist and gneiss: SM, ML, saprolite)
50-2000
Martin (1977)
a
After Canadian Foundation Engineering Manual , Part I 1978, unless otherwise noted. (Reprinted with permis-
sion of the National Research Council of Canada.)
TABLE 3.30
Rheological Factor
for Various Soil Conditions a
α
Peat
Clay
Silt
Sand
Sand and
Gravel
Material
E c / P L
α
E c / P L
α
E c / P L
α
E c / P L
α
E c / P L
α
Preconsolidated
1
16
1
14
0.67
12
0.5
10
0.33
Normally consolidated
1
9-16
0.67
8-14
0.5
7-12
0.33
6-10
0.25
Underconsolidated
7-9
0.5
5-8
0.5
5-7
0.50
0.25
a
Menard, L.F., Proceedings of the 6th International Conference on Soil Mechanics and Foundation Engineering ,
Montreal, Vol. 2, 1965, pp. 295-299.
Settlement analysis of shallow foundations (CGS, 1978; Menard, 1972).
Analysis of deep foundations (CGS, 1978; Menard, 1972).
Estimating horizontal subgrade reaction modulus k h (Poulos, 1971):
k h
0.8 E c / d
(3.78)
where d is the pile diameter.
Limitations of Pressuremeter Test Data
The modulus is valid only for the linear portion of soil behavior ( P f in Figure 3.87) .
Stratified or otherwise anisotropic materials may have modulus values much lower in the
vertical direction than in the horizontal direction. Since foundation stresses are applied
vertically in most cases, values for E may be overestimated from pressuremeter tests.
Stiffness of the device may be significant compared with the compressibility of the
tested material, as in very loose sands, soft clay, or organic soils. Borehole wall disturbance
and irregularities greatly affect test results. Modulus values should be correlated with data
obtained by other test methods.
 
 
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