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configuration does not provide separation of the layers' response as was

obtained with the Dynaflect. A modified FWD system utilizing a dual

loading system appears worth pursuing in future NDT research.

 6.7.3.2 Development of Prediction Equations. Although tuning of

the FWD deflection basins was not as good as that of the Dynaflect, the

tuned data were used to develop new equations in the hope of improving

those presented in Section 4.3.3. The FWD prediction equations pre-

sented in this section and that of Section 4.3.3 may be used for the

prediction of the initial or "seed" moduli for subsequent use in itera-

tive elastic multilayered computer programs.

 The range of layer moduli and thicknesses are as follows:

 80.0 < E < 400.0 ksi and 1.5 < t < 8.5 in.

 31.0 < E < 95.0 ksi and 6.0 < t2 < 24.0 in.

 12.0 < E3 < 80.0 ksi and 12.0 < t3 < 17.0 in.

 7.0 < E < 130.0 ksi and t4 = semi-infinite.

 The corresponding range of deflections (9-kip FWD load) as listed

in Table 6.11 are:

 8.58 < D1 < 29.54 mils

 3.51 < D2 < 17.81 mils

 2.16 < D3 < 14.67 mils

 1.16 < D4 < 11.03 mils

 0.65 < 0D < 8.80 mils

 0.41 < D6 < 6.99 mils

 0.31 < D7 < 5.56 mils

The range of parameters listed above are slightly different from those

used in the theoretical analysis. The subbase and subgrade moduli

ranges are increased here. Also, the base course thickness is increased