The four most probable causes of footing set-
tance from the footings to the top of the enclo-
tlement are viscous flow or densification of the
sure, and a surveyor's rod to tie the enclosure top
of footing A4 using the transit. The tape length
subfooting snow as a result of the weight of the
was corrected for temperature effect (11.61 106
building, mixed matrix composition of the sup-
cm/cmC).
porting snow, the influence of the presence of
Measuring footing tilts was also a task nor-
meltwater and runoff in and around the footing
mally assigned to the survey team. For those
enclosures, and differences in overburden pres-
measurements, a self-leveling level was mounted
sure of the surrounding snow. All four of these
conditions existed to various degrees at DYE-2
on a special monopod mount and used to deter-
during the time span under consideration. Uni-
mine elevations to the nearest 0.2 cm at four fixed
form settlement of the building and structure is
points at the footing corners. The level was
not as serious a problem as differential settle-
located on the centerline of the footing and the
ment, and so was not considered an important
four points at the corners of the footing refer-
factor contributing to the generation of stress in
enced to this point. This point was also used as
the structure. Differential settlement, such as that
the footing settlement datum point for each col-
caused by an inhomogeneous snow matrix, melt-
umn. Elevations for the four points were
water pooling in the footings, variable densifica-
recorded and rechecked. Calculations for tilts
tion of the supporting snow, and uneven load-
along and across the columns were later made
ing, was of more concern because it would likely
using these data. Data for settlement and tilts can
result in the generation or exacerbation of
be found in Walsh (1992).
Footing settlements at DYE-2 were very linear.
stresses in the supporting structure.
Table 3 indicates linear correlation coefficients
All footing settlements were measured rela-
greater than 0.985 for all columns for the years
tive to the footing below column A4. In 1982,
after DYE-2 was moved, the footings were all the
1982 through 1988. Averaged coefficients are
at the same elevation. Settlements were mea-
greater than 0.995. This signifies a very high
sured using a transit on the snow surface below
degree of correlation and thus indicates that the
the building, a tape measure to measure the dis-
footings are settling in a linear manner, although
Table 3. Footing settlements (centimeters).
Year/Column
A1
A2
A3
A4*
Average
A-side data
1982
0
0
0
0
0
1983
8.2
5.8
3
0
5.7
1984
15.8
10.4
4.9
0
10.4
1985
21.3
15.2
6.1
0
14.2
1986
29.6
18.9
10.4
0
19.6
1987
35.1
22.6
12.2
0
23.3
1988
41.8
25.6
14
0
27.1
Rate (cm/yr)
6.89
4.25
2.35
0
4.5
Correlation
0.9972
0.9897 0.9851 N/A
0.996
N1
N2
N3
N4
Average
N-side data
1982
0
0
0
0
0
1983
9.1
8.2
6.7
3
6.75
1984
19.8
17.1
14.3
6.4
14.4
1985
29.9
25
22.9
11.3
22.28
1986
41.1
34.1
28.7
15.8
29.93
1987
51.8
43
36
20.4
37.8
1988
61.3
52.4
44.2
26.8
46.18
Rate (cm/yr)
10.38
8.71
7.34
4.45
7.72
Correlation
0.9994
0.9995
0.9987
0.9886
0.9993
* A4 is reference footing and not included in averages, rates,
or linear correlation factor calculations
10
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