Table 7.9 Effect of Varying Subgrade Stiffness on Dynaflect Deflections on SR 26A
Number
of
Layers
Subgrade
Modulus*
(ksi)
Dynaflect Deflections (mils)
D
l
D
2
D
3
D
4
D
5
D
6
D
7
D
8
D
9
D
10
**

0.87

0.81
0.77

0.68
0.61
0.53
0.45
0.39
4(a)
37.4
0.63
0.49
0.47
0.45
0.41
0.36
0.32
0.26
0.20
0.15
50>)
18.9
0.80
0.66
0.64
0.62
0.58
0.53
0.49
0.42
0.34
0.29
6(c)
2.6
1.84
1.71
1.69
1.67
1.62
1.57
1.52
1.44
1.34
1.25
7(d)
23.1
0.93
0.79
0.77
0.75
0.71
0.66
0.62
0.54
0.45
0.38
*
**
(a)
(b)
(c)
(d)
Semi-infinite subgrade modulus using Dynaflect modulus qc correlation in Table 7.5 with
Ex = 171.5 ksi; E2 = 105.0 ksi; E3 = 70.0 ksi; t: = 8.0 in.; t2 = 9.0 in.; t3 = 12.0 in.
Field measured Dynaflect deflections
4-layer: E4 = 37.4 ksi and t4 = 
5-layer: E4 = 37.4 ksi; E5 = 18.9 ksi; t4 = 10.4 in. and tg = >
6-layer: E4 = 37.4 ksi; E5 = 18.9 ksi; Eg = 2.6 ksi; t4 = 10.4 in.; tg = 19.7 in. and tg = 
7-layer: E4 = 37.4 ksi; Eg = 18.9 ksi; Eg = 2.6 ksi; E? = 23.1 ksi; t4 10.4 in.; tg = 19.7 in.;
t6 = 29.5 in. and t? =
00