file in Figure 13. We also installed an immersion
4 88.57 ft
thermocouple and a flow meter at this location.
W
E
Sewer Pipe
3 87.98 ft
As before, this flow meter does not appear to be
2
working. The thermocouple layout at the main
1 87.31 ft
test section will enable us to characterize the ther-
mal environment around the shield. The control
string will give us temperatures that we would
expect to find in an undisturbed area. The tem-
peratures obtained at the surface of the test sec-
tion will be used as our surface boundary tem-
peratures in the numerical model, and the
temperatures from the immersion thermocouple
will be used as our pipe boundary temperatures.
Three more thermocouples were installed at
the site. One is on the normally dry portion of a
hydrant standpipe just above the main test sec-
tion at about 104 m (340 ft). There is an immer-
Sewer Pipe
sion thermocouple at the end of the pipeline at
125 m (410 ft) and an outside air temperature
thermocouple off the outside north wall at 73
Labossiere Street. We planned to compare air and
surface temperatures using this thermocouple and
Figure 12. Sewer line crossing with thermocouple
the previously mentioned surface thermocouples
layout.
at the main test section.
Control 1
PRELIMINARY DATA
String 2
14
3
PVT
15
4
Air temperatures
5
6
and frost penetration
16
331.81 ft
The winter of 199495 was unusu-
17
7
ally warm and was therefore not an
18
34
optimum test for the shielding con-
8
19
3.43 ft
cept. Some of the temperatures col-
35
9
lected from the beginning of data col-
20
21
25
lection on 9 September 1994 until 17
10
36
4.96 ft
26
22
32
11
March 1995 are shown in Figure 14.
27
5.0 ft
12
37
28
Here the outside air temperature is
23
6.75 ft
compared with the numerical sur-
386.48 ft 24
29
face boundary temperature used in
40
7.05 fftt
the design model. As mentioned pre-
viously, this FE boundary tempera-
39
41
7.63 ft
ture was determined from air tem-
Figure 13. Thermocouple layout at the test site.
42
9.05 ft
perature records in the Berlin area. It
can be seen that the numerical tem-
(80 ft). The sewer line crossing at 70.4 m (231 ft)
peratures were generally colder than the air tem-
gave us an opportunity to measure the effect, if
peratures. Probably just as important is that when
any, that the relatively warmer sewer line would
we did experience cold temperatures, they did
have on the temperatures within the shield. Fig-
not last very long. Notice that the temperatures
above 0C tend to last longer than those below
ure 12 shows the sewer line and the placement of
0C, and there is never a prolonged cold spell.
the four thermocouples at this location.
The main instrumentation section was at ap-
Under this type of temperature profile the ground
proximately 73 m (240 ft) along the pipe. Here we
never has a chance to maintain any appreciable
installed 40 thermocouples, as shown in the pro-
frost penetration. In our situation in ledge, the
11
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