Table 18. Midwinter thaw index summations.
Water table
Freezing
Midwinter thaw index
depth
index
(Total)
(> 30 DD)
C(F)-days
C(F)-days
C(F)-days
Year
m (ft)
6970
1.5
(4.8)
1191
(2144)
25.5
(45.9)
0.0
7071
1.3
(4.2)
1152
(2074)
41.0
(73.8)
0.0
7172
1.1
(3.6)
1274
(2294)
50.0
(90.0)
19.4
(35.0)
7273
1.2
(4.0)
839
(1510)
21.5
(38.7)
0.0
7374
11.3
(4.2)
923
(1661)
56.0
(100.8)
22.3
(40.1)
7475
1.4
(4.6)
968
(1743)
35.0
(63.0)
14.2
(25.5)
7576
11.3
(4.2)
931
(1675)
67.0
(120.6)
20.7
(37.2)
7677
1.6
(5.3)
1256
(2261)
44.0
(79.2)
0.0
7778
1.1
(3.7)
1331
(2395)
26.5
(47.7)
0.0
7879
1.2
(3.8)
1477
(2658)
52.0
(93.6)
18.0
(32.4)
7980
1.2
(3.8)
903
(1625)
32.0
(57.6)
0.0
8081
1.2
(4.0)
666
(1199)
41.0
(73.8)
17.5
(31.5)
8182
1.8
(6.0)
1227
(2209)
31.5
(56.7)
21.9
(39.4)
8283
11.2
(3.9)
589
(1061)
92.5
(166.5)
75.0
(135.0)
8384
1.0
(3.3)
1179
(2123)
40.0
(72.0)
34.7
(62.4)
8485
1.0
(3.3)
942
(1696)
40.0
(72.0)
22.9
(41.2)
8586
1.0
(3.2)
1197
(2154)
29.0
(52.2)
0.0
8687
10.9
(3.0)
467
(841)
65.0
(117.0)
40.1
(72.1)
8788
11.5
(4.8)
898
(1616)
79.0
(142.2)
54.2
(97.6)
8889
1.5
(4.9)
1032
(1858)
49.0
(88.2)
0.0
8990
11.4
(4.7)
750
(1350)
70.5
(126.9)
27.0
(48.6)
Table 19. Average percentage of total yearly dam-
In the full-depth cross section, horizontal strain
age accumulated during four seasons.
damage occurred primarily in the winter, with
slightly less in the spring, and some additional
Accumulated damage (% of total)
damage in the fall. Both vertical strain models
Section/model
Fall Winter
Spring Summer
predicted damage in the full-depth section to oc-
Conventional
cur mainly in the winter, with some in the spring.
AIH
22
31
45
2
The Asphalt Institute vertical strain model also
AIV
0
40
60
0
predicted additional amounts of summer damage.
CEV
0
42
58
0
Full depth
AIH
16
51
32
1
DISCUSSION AND
RECOMMENDATIONS
AIV
2
44
16
38
CEV
0
80
20
0
The Phase 1 modeling series indicated signifi-
Notes:
cantly different performance by the different test
AIH = Asphalt Institute horizontal (MS-11)
sections and highly variable results depending on
AIV = Asphalt Institute vertical (MS-1)
the performance model applied (Table 13). The
CEV = Corps of Engineers vertical
simulated performance of the test sections was
section, a majority occurred in the spring, while
also significantly affected by the subgrade condi-
the remainder occurred in the winter (Table 19).
tions, e.g., density, soil moisture and water table
Horizontal strain damage in the conventional cross
depth. For example, compare the model predic-
section also occurred mainly in the spring, with
tions using the Asphalt Institute MS-1 horizontal
additional significant amounts in both the winter
strain criteria. For case f4w6, the full-depth 5-
and fall, and very small amounts in the summer.
year section with the 1206 subgrade in its opti-
33
Previous Page
