lated with a combination of the Ullidtz model at
water table depth was applied such that the maxi-
above 1C temperatures and the Schmidt model at
mum precipitation produced the shallowest water
colder temperatures.
table at 0.91 m (3 ft) below the surface and the
minimum precipitation produced the deepest wa-
Environmental conditions
ter table at 1.82 m (6 ft). The water table was held
The series simulated the 21-year time period
constant throughout the simulation at the depth
196970 to 198990, using a combination of re-
determined by this relationship. Figure 17 shows
corded air temperatures and an estimated position
the distribution of estimated water table and freeze
of the water table. The simulations started on 1
index for this period.
October of the first year and proceeded for 365
days, using mean daily air temperatures recorded
Results
at Buffalo, Minnesota, applied as a step condition
As in previous simulation series, there was a
for 24-hr periods. The depth to the water table
wide variation in the damage amounts predicted
was varied based on the total precipitation accu-
by the different models (Table 17). In general,
mulated at St. Cloud, Minnesota, during the thaw
less damage related to horizontal strain was pre-
season prior to the simulated freeze season. An
dicted in the full-depth design than in the conven-
inverse relationship between precipitation and
tional design. On the other hand, when all other
Table 17. Results of 21-year freezing index/water table series.
Maximum
Applications to failure (millions)
Water table
Freezing
Freeze/thaw freeze depth Horizontal strain
Vertical strain
depth
index
events in into subgrade Asphalt cracking
Subgrade rutting
C (F)-days subgrade
Year
m (ft)
(cm)
CEH
AIH-MS11 CEV AIV-MS1
A. Full depth (F4)
6970
1.5 (4.8)
1191 (2144)
2
91.8
18.20
66.00
0.21
5.38
7071
1.3 (4.2)
1152 (2074)
4
91.8
18.02
52.59
0.34
8.23
7172
1.1 (3.6)
1274 (2294)
2
91.8
15.16
45.02
0.31
7.64
7273
1.2 (4.0)
839 (1510)
2
69.8
18.97
50.69
0.37
7.72
7374
1.3 (4.2)
923 (1661)
2
77.8
17.80
51.48
0.78
10.97
7475
1.4 (4.6)
968 (1743)
3
81.8
17.21
47.93
0.18
5.47
7576
1.3 (4.2)
931 (1675)
3
73.8
16.83
52.26
0.16
4.15
7677
1.6 (5.3)
1256 (2261)
4
107.8
17.92
62.38
0.16
4.87
7778
1.1 (3.7)
1331 (2395)
1
91.8
13.88
60.22
0.10
3.01
7879
1.2 (3.8)
1477 (2658)
3
99.8
17.66
51.36
6.66
17.18
7980
1.2 (3.8)
903 (1625)
5
79.8
16.67
43.10
0.19
5.30
8081
1.2 (4.0)
666 (1199)
3
67.8
17.15
42.63
0.26
7.72
8182
1.8 (6.0)
1227 (2209)
3
107.8
16.29
47.92
0.04
1.44
8283
1.2 (3.9)
589 (1061)
8
63.8
16.73
34.26
0.11
3.71
8384
1.0 (3.3)
1179 (2123)
2
81.8
16.86
48.96
0.12
3.50
8485
1.0 (3.3)
942 (1696)
3
81.8
16.08
44.68
0.15
4.31
8586
1.0 (3.2)
1197 (2154)
2
81.8
17.67
71.27
0.79
11.48
8687
0.9 (3.0)
467 (841)
4
45.8
15.91
33.52
0.48
8.44
8788
1.5 (4.8)
898 (1616)
4
87.8
16.91
48.28
0.34
6.15
8889
1.5 (4.9)
1032 (1858)
4
87.8
17.57
50.53
0.26
7.19
8990
1.4 (4.7)
750 (1350)
7
65.8
16.50
37.45
0.25
6.83
Notes:
CEH = Corps of Engineers (horizontal)
CEV = Corps of Engineers (vertical)
AIH-MS11 = Asphalt Institute (MS-11)
AIV = Asphalt Institute (MS-1)
ND = no damage
Traffic simulated at rate of 660,000 ESAL applications/yr.
29
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