118
, 0.97871
E = 34.8891 (D ) Eqn. 4.27
4 8
(N = 400 and R2 = 0.9996)
In Equations 4.25 through 4.27, like the previous equations, modulus is
in ksi, and deflections are in mils. Again, Dg and D? are deflections
from sensors located at radial distances of 47.2 and 63.0 in., respec
tively, in the conventional geophone spacings utilized by the FD0T.
However, Dg is an additional sensor located at a radial distance of 72.0
in. which was included in this study. The FD0T does not have sensor 8
measurement (Dg) in their current sensor array system.
Additional multiple linear regression analyses (39) were performed
to see if there were any interactions among Dg, D?, and Dg which could
provide an optimum relationship for the prediction of E^. The following
two logarithmic equations were obtained:
log (E ) = 1.51999 + 0.622145 log (D ) 1.58542 log (D ) Eqn. 4.28
4 6 7
(N = 400 and R2 = 0.9995)
log (E ) = 1.48914 + 0.893689 log (D ) 1.86276 log (D )
(N = 400 and R2 = 0.9997) Eqn. 4.29
An equation combining all three independent variables Dg, D?, and
Dq was not found from the multiple linear regression analysis. The
applicable range of parameters (layer moduli and thicknesses) for
Equations 4.25 through 4.29 are presented above. However, due to the
unique relationship between E4 and the FWD sensor deflections, these