308
Table 7.5 Relationship Between Resilient Modulus,
and Cone Resistance, qc
Dynaflect
Moduli
FWD Moduli
Layer
Regression*
Equation
N
R2
Regression*
Equation
N
R2
Base
E2 = 13.992 qc
i0(a)
0.971
E2 = 9.073 qc
12
0.921
Subbase
E3 = 12.987 qc
11(b)
0.954
E3 = 7.467 qc
12(c)
0.942
Subgrade
E, = 6.699 qc
12(d)
0.770
E^ = 6.853 qc
13(e)
0.856
ALL
Er = 12.881 qc
33
0.931
E^ = 8.356 qc
37
0.910
* Some of the test pavements were deleted in the regression analysis.
Pavements deleted are:
(a) SR 12 and SR 15C M.P. 0.055
(b) US 301 and SR 15C M.P. 0.055 and 0.065
(c) SR 15C M.P. 0.065
(d) US 301 and I-10A
(e) I-10A
correlation since a composite (average) subgrade modulus from the NOT
was used in the analysis.
7.4.3 Correlation of Resilient Moduli with Dilatometer Modulus
Similar comparisons with the dilatometer modulus, Eq, for the sub
base and subgrade layers were made. These are presented in Tables 7.6
and 7.7, respectively. The ratios of tuned moduli to Eq for the subbase
vary more than that of the subgrade. Also the ratios obtained for the
subgrade are close to unity, especially for the pavement sections with
weak subgrade layers. This suggests that the dilatometer modulus may be
directly related to the in situ elastic (resilient) modulus of soft
subgrade soils.