400
CWA, Mosinee
Air Freezing Index (1100 C degree-days)
0
Beginning of Spring Thaw
(29 Mar)
400
Beginning of Freezing
800
Period (17 Nov)
30 Sep
30 Oct
29 Nov
29 Dec
28 Jan
27 Feb
29 Mar
28 Apr
28 May
1985
1986
a. Central Wisconsin Airport.
400
Appleton
Air Freezing Index (920 C degree-days)
0
400
Beginning of Freezing
Period (19 Nov)
Beginning of Spring Thaw
(24 Mar)
800
30 Sep
30 Oct
29 Nov
29 Dec
28 Jan
27 Feb
29 Mar
28 Apr
28 May
1985
1986
b. Outagamie County Airport.
Figure 6. Air-freezing indices.
ing index published in Army TM 5-818-2 for these
around 2000 mm and at OCA around 1300 mm. The
areas ranges between 830 and 1110C days, which
measured subsurface temperatures indicate that thaw
means that the air-freezing index in the winter of
began at CWA around 29 March. The ground was
19851986 was close to that. The air-freezing season,
completely thawed by the second week of April. At
as indicated in the above two figures, ended around 24
OCA, when subsurface temperature measurements
March 1986 at OCA and 29 March 1986 at CWA.
were made in the spring, thaw had already started. The
Using the temperature measurements gathered
ground was completely thawed by the first week of
from the various thermocouple locations, we deter-
April.
mined frost and thaw depth, which we assumed to be
where the temperature was 0C. Frost depths at the
FWD DATA ANALYSIS
beginning of the winter were calculated for some of
the locations and are also presented in Janoo and Berg
Falling weight deflection measurements were con-
(1966). A summary of the frost and thaw penetration
ducted at four locations on a slab. These were at 1) the
depths at CWA and OCA is presented in Figure 7. The
middle, 2) across the transverse joint, 3) across the
maximum measured frost penetration at CWA ranged
longitudinal joint and 4) across the diagonal on one
6
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