5000

Boeing 757

y = 41732x 0.5493

4000

R 2 = 0.69

3000

2000

1000

0

400

800

1200

1600

Subgrade Modulus ( MPa )

5000

MD DC 9

y = 10973x 0.3744

4000

R 2 = 0.54

3000

2000

1000

0

200

400

600

800

k, Coefficient of Subgrade Reaction (MN/m3 )

Since we found damage to be a function of thickness, σh

the other relationships. Small differences were obtained

for the Boeing 757 and the MD-DC9.

was developed as a function of *E*s or *k *and the coeffi-

The following equation could be used to estimate the

cient of thickness. We found that the correlations in-

horizontal stress σh as a function of the subgrade modu-

creased when thickness was taken into consideration.

lus *E*s (MPa) during the spring thaw

σh= 7360 1.5*E*s 17*t*

σh =

41, 732 *E*s0.549 .

or

We observed a similar trend between the horizontal

σh= 7389 13.02*k * 17.5*t*

strain and the coefficient of subgrade reaction. The fol-

lowing equation could be used to estimate the horizontal

stress (σh) as a function of the coefficient of subgrade

where *t *is PCC thickness (mm).

reaction, *k *(MN/m3) during the spring thaw

The relationship between the total basin area and the

horizontal stresses (σh) at the bottom of the PCC layer is

σ h = 12, 436 *k *0.411.

shown in Figure 35. A linear trend was applied to the

28

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