Thermal influence of steel posts on the ground temperature regime during the winter: a field experiment

(1)

Publisher’s version / Version de l'éditeur:

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

Questions? Contact the NRC Publications Archive team at

PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.

https://publications-cnrc.canada.ca/fra/droits

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

Internal Report (National Research Council of Canada. Division of Building

Research), 1970-01-01

READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.canada.ca/eng/copyright

NRC Publications Archive Record / Notice des Archives des publications du CNRC :

https://nrc-publications.canada.ca/eng/view/object/?id=08d4e06e-0b73-483a-8a61-cec53fc8ec8f https://publications-cnrc.canada.ca/fra/voir/objet/?id=08d4e06e-0b73-483a-8a61-cec53fc8ec8f

NRC Publications Archive

Archives des publications du CNRC

For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous.

https://doi.org/10.4224/20386556

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

Thermal influence of steel posts on the ground temperature regime

during the winter: a field experiment

(2)

NATIONAL RESEARCH COUNCIL OF CANADA DIVISION OF BUILDING RESEARCH

THERMAL INFLUENCE OF STEEL POSTS ONTHE GROUND

TEMPERATURE REGIME DURING THE WINTER - A FIELD EXPERIMENT

by

E. Penner

.. ANALYZED

Internal Report No. 373 of the

Division of Building Research

OTTAWA January 1970

(3)

PREFACE

Frost heaving around footings of transmission tower s is thought to be aggravated by exc essive heat withdrawal from the soil by the steel superstructures. The study described in this report is a first attempt to assess the severity of the problem under relatively simple conditions and was undertaken in respons e to inquiries by designers.

Mr. Penner, a research officer with the geotech-nical Section of the Division of Building Research, has been involved in frost action research since joining the Division in 1953.

Ottawa

January 1970

N. B. Hutcheon Director.

(4)

THERMAL INFLUENCE OF STEEL POSTS ON THE GROUND

TEMPERATURE REGIME DURING THE WINTER - A FIELD EXPERIMENT by

E. Penner

Footings of unheated structures are normally placed below the depth of maximum seasonal frost penetration as a method of preventing frost heav-ing. When the thermal properties of the structure are different from those of the soil, it is possible that there may be an influence on the ground thermal regime during the winter because the superstructure is in a colder environ-ment than the foundation. This possibility exists in the case of self-supporting

steel transmission line towers where the steel members of the super-structure extend into the ground and are attached rigidly to footings at some depth. Excessive heaving has occurred in the case of tower foundations of transmission lines and it has been suggested that the steel tower legs may be partly responsible for the severe frost penetration and heave problem. How much of this can be attributed to the influenc e of the steel posts on the ground thermal regime is not known.

An analytical assessment of the additional heat loss from the soil induced by the structure under field conditions cannot readily be carried out for many reasons. Factors which contribute in combination to the com-plexity of the problem are the variability of the daily air temperature, the changes in thermal conduction when the soil freezes, movement of water to the freezing plane which increases the i.nsitu water content of the frozen zone, the variable snow cover depth, the thermal properties of the complex organic cover in northern regions, and many other s. It has not been pos sible to ex-tend the results of the model studies carried out by Brown (1) in a meaning-ful way to the conditions described above. A simple field experiment was undertaken, therefore, to evaluate the influence of steel tower legs on the environment in the surrounding soil under one particular set of conditions. This note describes the experiment and gives an assessment of the influence based on one winter's results.

METHODS AND MATERIALS Site and Soil Conditions

The site of the experiment is in the eastern outskirts of Ottawa on the National Research Council's Montreal Road property. The soil is a postglacial marine deposit with a natural grass cover. It has an autumn moisture content of about 44 per cent and consists of approximately 70 per cent clay size particles and 30 per cent silt. The average apparent density is 1. 7 6 g m

I

c m3 (11 0 1b

I

ft3 ) •

(5)

2

-Design of Experiment and Installation

The steel posts that were used to sirnulate the tower legs con-sisted of four 12-ft lengths of steel angles 3± x 3/8 in. bolted together in the arrangement shown in Figure 1 a. The posts were driven into

6-in. augered holes to a depth of 6 ft and backfilled as closely as possible to the original density. The length of post exposed to the atmosphere was also 6 ft.

To rn e a s u r e the temperatures along the steel post, 20-gauge cop-per constantan thermocouples were located at I-it intervals along the 12-ft length and were positioned as shown in Figure 1 b. The thermal voltages were recorded daily at 0815 hr with a millivolt data acquisition systern. Air temperatures wer e obtained from. the Division's meteorological station located a few hundred yards from the site.

Two such steel posts were installed 20 it apart (Figure 1 c). Thermo-couples were used to rn e a s u r e soil temperatures to a depth of 6 it and at various distances from the posts. These thermocouples were placed on

I-in. diameter wooden dowels with an 18-in. length of the thermocouple wrapped around the dowel at each level to avoid heat conduction errors in the measurements. The centre string (SP 6, Figure 1 c), located half-way between the steel posts, was considered to be a control not influenced by the thermal effects of the steel posts. Natural snow cover was allowed to accumulate and the area was left undisturbed throughout the winter period. Snow depth gauges were located above SP4 and SP 8 (Figure 1 c)

4 it from each steel post. RESULTS

Based on thermal considerations the portion of the posts above the ground surface was sufficiently long to simulate tower legs which are nor-mally much longer than those used in this experiment. This was substan-tiated by the experimental results that showed, that the top 4 it of all the posts were essentially at the same temperature. Figure 2 shows the temperature distribution along the steel posts; this is representative of the usual condition, although some anomalies did occur during abrupt air temperature changes or in short periods of bright sunlight.

Figure 3 a shows the daily air temperatures at the DBR meteorolog-ical site located a few hundred yards from the experimental site. Figure

3 b shows the daily ground temperatures of the control string (SP 6) lo-cated halfway between the steel posts. It should be noted that no freezing took place in the ground at this site under the undisturbed snow cover during the 1968-69 winter.

Figures 4 and 5 give the temperature differences between the control string and the below-ground portion of the steel posts at intermediate locations at the various depths. Temperature differences plotted above the base lines

(6)

- 3

-indicate the temperatures of these locations were colder than the control string; this is attributed to the influence of the steel posts. A thermal end effect is noted on the steel posts. This is thought to be because of the different heat flow patterns at the ends of the posts as compared to the sides of the posts where only lateral heat flow took place.

Table 1 gives the average temperature of each location at all depths between 23 November 1968 and 31 March 1969, based on daily

0815 hr readings. This Table also gives average temperature differenc es between the control and the other locations. These results have been plotted in Figure 6 to display clearly the pattern of influence the steel posts had on the ground thermal regirne. The therrnal behaviour of the two steel posts was s irniIa r but there were some differences resulting largely fr orn the uneven snow cover.

Figure 7 is a series of plots which gives the position of the 00

C isotherm. at various distances from both steel posts as a function of time. The depth of snow cover for the entire period is given in the same figure. Near the steel post, SP 1 position A, the snow cover reached a depth of 28 in.; at Position B, 23 in.; hence, s orn e differences in the thermal regime at the two sites m ight be expected. SP 6, the control thermocouple string, had a snow depth COver somewhere in between these two extremes.

It should be rnentioned also that there was a funnel-shaped cavity in the snow cover at each post due to wind action. The funnel was about

18 in. in diarneter at the top and gradually narrowed down to the size of the posts near the ground surface. These funnels were not interfered with because they were a natural phenomenon that would probably occur around any similar structure exposed to the same field conditions in the winter.

DISCUSSION

It can be seen from. Figure 7 that 6 in. fr orn the posts the frostline (based on the O°C isotherm) penetrated 1. 2 to 1. 4 ft. One ft from the posts it penetrated 0.8 to 1.0 ft. No frost penetration occurred 2 it from the posts (Position A), but at Position B it penetrated to a depth of 0.6 ft, and 4 ft from the posts, to 0.2 ft.

The temperature of the steel posts dropped to 0° C at depths of 1.6 to 1.8 ft from the ground surface. Thus the freezing plane 6 in. from the posts was 0.4 ft higher in the profile than on the steel posts and 0.8 ft higher at a 12-in. distance. Figure 8 shows, in section, the dimensions of the cone of soil frozen at each steel post. As mentioned previously the slightly larger cone at Position B is probably a result of the shallower snow depth at that location. In the area halfway between the steel posts and not influenced by

(7)

4

-All the freey,ing in the soil as shown in Figure 8 was induced I)y

the steel posts and hence the direction of the heat I l ow involved in the freezing process was toward the posts. The forces developed in ice lens growth are parallel to the direction of heat flow. Based on this, the direction of heave would not be in a vertical direction but rather would follow the lines of heat flow. Observations during the latter part of the winter showed that the posts had, in fact, not moved. The amount of frost heaving associated with vertical penetration of the frost line in these

soils is in excess of 1 in. per foot of frost penetration hence at least

Ii

in. of heave should have been anticipated in the present case. CONCLUSION

The results indicate that steel posts installed with both above- and below-ground portions have a substantial thermal influence on the ground in a l'egion of seasonal frost. The results fr orn one winter when no natural

frost penetration occurred due to snow cover showed that 6 in. from the post the frostline penetrated to a depth of from 1.2 to 1.4 it, and 12 in. from the post it penetrated 0.8 to 1 ft. At the surface of the ground in-duced soil freezing extended 2 it laterally in one case and beyond that in the other.

It rnay be tentatively concluded from one w inte r ' s results that the heat flow pattern induced was not conducive to vertical heaving of the posts.

The r rn a l rnoa s u r ern erit s will be continued at this site for at least one rrio r e year to obtain results for different winters. It is hoped that such results will be helpful for predicting the thermal influence by steel posts of dif-ferent dimensions and configuration for other regions in Canada where both climate and soil conditions are different.

REFERENCE

(1) Brown, W. G. Thermal rnodel tests for probe conch...ction errors In ground-temperature measurement. Ge o tec hniqu e, Vol. XIII, No.3 September 1963, p. 241-249.

(8)

Table 1

AVERAGE TEMP FOR WINTER SEASON AND TEMPERATURE DIFFERENCES BETWEEN CONTROL AND VARIOUS LOCATIONS, NOVEMBER 23, 1968--MARCH 31, 1969

HORIZONTAL DIS. TO STEEL POST SP 1 HORIZONTAL DIS. TO STEEL POST SP 11

STEEL STEEL

CONTROL POST 1/2" 1 ' 2 ' 4 ' 4I _2' _{1 '} 1/2" POST

SP 6 SP 1 SP 2 SP 3 SP 4 SP 5 SP 7 SP 8 SP 9 SP 10 SP 11

DEPTH T* T t,T ,', T tiT T t,T T t,T T tT T tiT T tiT T t,T T t,T T tiT

0 0.26 -2.41 2.67 -0.841.10 -0.39 0.65 0.34 0.08 0.30 0.04 0.14 0.12 -0.16 0.42 -0.76 1.02 -1.752.0 -2.84 3.10 1 ' 1. 36 0.16 1.20 0.56 0.80 0.79 0.57 1.12 0.24 1.41 0.05 1.12 0.24 0.85 0.51 0.56 0.80 o .18 1. 1E -0.10 1.46 2I _2.80 _{1.84 0.94} _{2.16 0.64} _{2.25 0.55 2.43 0.37 2.67 0.13} _{2.47 0.33} _{2.00 0.80} _{1.91 0.88} 1.76 _ＱＮＰｾ 1.76 ＱＮＰｾ 3I _4.06 _{3.43 0.63} _{3.58 0.48} _{3.67 0.39 3.79 0.27 4.00 0.06} 3.78 0.28 3.47 0.59 3.41 0.65 3.29 0.7 3.26 0.80 4I 5.25 4.63 0.62 4.85 0.40 4.91 0.34 5.01 0.24 5.22 0.03 5.00 0.25 4.720.54 4.68 0.57 4.58 0.68 4.54 0.69 5I _6.25 _{5.59 0.66} 5.87 0.38 _{5.93 0.32 6.10 0.15 6.26 0.01} 6.05 0.20 5.84 0.41 5.75 0.50 5.64 0.6C 5.50 0.75 6I _7.13 6.15 0.98 6.78 0.35 6.85 0.28 6.98 0.15 7.14 0.01 6.96 0.17 6.81 0.32 6.78 0.40 6.60 0.5 7.10 1.03 * (T), TEMP. °c

: (t,T), DIFFERENCE IN TEMPERATURE BETWEEN THIS LOCATION AND THE CONTROL SP 6, WHICH WPS LOCATED HALFWAY BETWEEN STEEL POSTS - IN CENTIGRADE DEGREES.

(9)

3

'/z·

SCALE:INCHES ; ;

,

o I 2 S THERMOCOUPLE IMBEDDED IN EPOXY RESIN , , STEEL PIPE ,

,

(0) ARRANGEMENT OF STEEL ANGLES IN SECTION (b) POSITIONING OF THERMOCOUPLES AT I FT INTERVALS ON STEEL POSTS IN SECTION

(c) EXPERI ME NTAL LAYOUT OF THERMOCOUPLES

-2' POSITION B

-I

SP8 SP9 SPIOSPII

-I'

ｾＮＭ

--'1--

r

-I

j

r

iIi

-ｾ

--1 --1--1_

1 11

I

1 I

I

SP7 9.7'

AIR TEMPERATURE I" THERMOCOUPLE - _ 20'

i

r

CONTROL

V

THERMOCOUPLE I

:!

I

-SP6 GROUND SURFACE 9.7' SP5 4' 2' 1...-STEEL ｾ POSTS

-POSITION A

I--

I'

Ｍｾ

- a"-_---i

_11 1

_I I I 1

- r - -

_{__1 1}

r

_•

i l l

I

ｾｃａｌｅｩＺ FEET i

- rI

i

0 I 2 S

- : 1

I

SPI SPZ SP3 SP4

....

u.

_.

w u 6

:

ｾ 5 en

W4

ｾｾ 3 ｾ 2 ｾｾｉ

o

....

u.. I w

u2

:

ｾ 3 en ｾＴ o ｾ 5 CD x 6

....

0.. W o FIGURE I

(10)

GROUND

TEMPERATURES

OF CONTROL,SP6

•..

ｾ ...•ｾ

..

ｾＮＬｾ

｜Ｚｾ｜ｾ

...

｜｜ｾ

\

..

｜｜ｾ｜Ｌ

...

\

\.

_..

\\\

_.

_\

\ 1\ \

o

4

8

4 o

-4

I I I I I

1-15.0°C

I I I I

,

_,

\ \

,

'

...

_...

-....

---16

-12

-8

TEMPERATURE,oC

-20

-24

···9 MAR 1969

._._. 28JAN 1969

---- 10 JAN 1969

-

26 DEC 1968

-

19 DEC 1968

NOTE: SP6 IS LOCATED 10' FROM

SPI

-28

to-LL..

12'

I I I I I I ( I I I I I I I f I I ; 'II \ \ 1 ,

3=

10

9 w

CD ｾ w

u

8 «

LL.. 0:: ｾ

en

i

i-19.7°C

i

-14.4°C

i

!

\

Ｔｾ

- ,...

w

'...

Ｎ｟Ｎ｟ＮｾＮ

ｾ

---CD C::llct'I\t:E

«

ｾｃｦ｜ｬｬｦｊｾ

__

0

to-LL..

ti

2 1-

28.5°C

«

LL.. 0:: ｾ

en

_

61

V I \ U U • •ｾ . J ' - J I " .- , : : : " " ｾ •

I

_ ac::: E....

FIGURE 2

TEMPERATURE DISTRIBUTION ON STEEL POST (SPI), AIR TEMPERATURES, AND GROUND

TEMPERATURES CONTROL (SP6) ON THE DAYS GIVEN AT 0815 HR

(11)

4 2 -2 u -4 o

_.

ｾ -6 ::::> !;i a: -8

....,

a.. ｾ -10 ...

t:

-12 ｾ a: ...., ｾ -14 -18 -20 -22 -24

(0)DAILY AVERAGE AIR TEMPERATURES 1968-69

(b) GROUND TEMPERATURE AT 7 DEPTHS OF THE CONTROL LOCATION (SP6) AS A FUNCTION OF TIME BASED ON 0815 HR READINGS FREEZING INDEX 1620 DEGREE DAYS 2 3 u ₄ 0

.

...., a: 5 ::::> ... ｾ a: ...., ₆ a.. ::E

....,

... ₇ 0 z ::::> ₈ 0 a: C) 10 II 12 13

NOV 68 DEC 68 JAN 69 FEB 69 MAR 69 APR 69

FIGURE 3

AIR AND GROUND TEMPERATURES 1968-69

(12)

(0) AT GROUND SURFACE II 10 9 8 7 6 5 4 6T,·C

ｾｦ［ｾ

(\(\ ,

I"....

oli.

r···..

ｾＺ

Ｒｾ '[ 0 ｾｾＮ ..:

"':j

'0.iｉｬｾ

.t...

ｾｾｾｾ ON STEEL POST 2

t

I[ 0

ｾＢ

＾ｾｾｾＧｾＺＮＬ｟｟ｾＮＮＬＬｾ

'I,

FT FRO. POST

2 I 0 ...--...--/ -...J

=:- ""--

J) IFTFROM POST

J

or

:::.:.-._.

.===.:.:.:.

.=.:._.--==-

ｾＺｾＺＺｾＺＺｾｾｾ

---=---=---},..,

AS" (.) _ _ _---",.,...'=="'... - - - - _ } , . . , AS" (.1

ｏｔＺＧＲ［ｾｾ

ＲＺ｛ｬｊｯｾ

l

-

J

Ｍ］Ｍ］ｾ

ＺＺＺＺｾＮＮＮ

_.. _{- -}ｾＮ｟Ｎ｟ＮｾＮ｟Ｎ｟Ｎ｟Ｎ｟Ｎ｟Ｎ｟Ｎ｟Ｎ｟Ｎ｟ＮＭＭＮ _=='

-

.

dT::

t

:[

rr

ｾｔＺｏＺｐｾｈＬｭ｟

2[

,J

__

__ .

｛ＭＭＭＭＭＭｾ

- - - -

-l

ｾ

0

］Ｚｾ］］］ｾｾ］Ｎｾ］ＭＺＮＺＮ］Ｎ｟Ｎ｟Ｎ］Ｚ

..._

2 I (d) 3 FT DEPTH

'::;

Ｚｦｾｏ｛ｾ

}SAME AS IN (a)

J

l

］ＭＭＭＺＺＭＭｾ

］ＭＭＺ｟Ｍ］ＺＮＺＺ］ｾ

__

ＭＮｾＭ］Ｚ

2

I[ ---.

(el 4 FT DEPTH ____

,:,,;[l

ｾ｛ｏ

'.===:::::::::.:::::::::::::::::::::=======-

}SAME AS IN (al

I[

J-

-'--"'-'-'_._'-'-'-'-'-'-'-'-'''''

O[

... ...----

« - - _-c,. 0 .eo •

OT.."

ＺｴＺｴＺｴ］］］］ｾ］ｾｾｾｾ］］］］

}SAME AS IN (0)

I:J

_._._.=...

ｾＮ｟Ｎ｟ＮＭＮ｟Ｎ｟Ｎ｟ＮｾＮＭ

oL

_ .

_

•

.eo_'" - • (g)6 FT DEPTH dT,oC I ｾｴＭＭＭＮＮＮＭＭ

It ot

.

ItO' ＭＭＭｾＭＭＭＭ - - - ' :

It aL

=.

Ｎ］Ｎ］ＮｾＮＭ］Ｎ］Ｚ］Ｎ｟ＮＭＭ

...

=-o -} , . . , AS " I.)

NOV 68 I DEC 68 I JAN 69 I FEB 69 , MAR 69 I

FIGURE 4

TEMPERATURE DIFFERENCES BETWEEN CONTROL, SP6I AND

STEEL POST, SPI, AND VARIOUS DISTANCES FROM SPI

(13)

(0) AT GROUND SURFACE (b) I FT DEPTH

...

;

::

...

....

ｾ

..

12 II 10 9 8 7 /IT,·C 6 6 5 5 4 5 4 4 3 2 321 2 I 0ＧＭＭＭＭＭＭＭｩｾｊｦ｟｟｟｟ｾ｟｟ｊｲＫＫＺＺ｟ｸ｟ＭＭＭＭｩＭ｟ＧＺＧｦ｟ｩｦｴｬ｟Ｍ｟Ｋ｟｟｟ＬＬＢ］｟ｴ＾ｲ｟｟ｩｾｴＮｍｉ｟ ON STEEL POST 2[ I[ 0 1/2 FT FROM POST 0 2 1

[Ole0 I FT FROM POST

[ 2 FT FROM POST 4 FT FROM POST /IT.C Ｔｾ

:;r

ｬｾ

It--...

,....:..-"''''''-7'''7>---'---=:.:.:....;.:..,''---..::.---:,-..,,,.,;,,.

;t

ｊＭＭＭＭｾ］］］ＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭ］ＭＮＮＮ］Ｎ

...

;.=::==;..

...-==.._._._

==:..:.:.. :

=::::::.:}

SAME AS IN (0)

.

ＮｾＮＭ｟ＮＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭｾＭＬＬＭＭｾＭＭＭＭＭＭＭＭＭＮＭＭＭＭＭＭ {dl 3 FT DEPTH

.

::

,...

_.

_..

}

ＯｉｔＬＮｾ

j

ｾＬＬＭ｛

__

］ＮＮＬＬＭＭＭＭＬ｟｟｟｟ｾ］

_ _

ｾＮＮＮＮＮＬＮｾ］］］ｾＺＺＺ［ＺＭＺＺ］ＺＺＭＭＧﾭ

ｉｾｊＭＭＭＭＺＭＭＭＭＭＭｾＭＺＺＭＭＭＭ］ＺＭＺ］ＭＭＭＭＭＺＭＭＭＭＭ

ｾｯｬＭ

ｾｾＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭｾＭＭＭＭＭＭＭＭＭｾ

.==.==:.===.==.====.==.}

SAME AS IN tal ｟Ｎ｟ＮＭＮＭＮ｟ＮＭＮＮＮＢＮＮＮＭＮ｟ＮｾＮ｟ ...

_._._._._.-/I

ｔＬＮｾｾｴｾ｛ＭＭＭＭＭＭＭＭＭ｣ＺＺＺＺ］］］］ＭＭＺＺＭＺＭＺＭ｣ＺＺＭ｣ＺＺＭＭＭＭＭﾭ

't 0t

-ｾｴ｟ｯ

...

ｾＭＢＧ］ｾＭＢＢＢＢ］］］］｟］ＭＭＭＭ］Ｍ］］］］］］］Ｍ

"",e,a. ' -. . .ee.... - _...ＭＮＮＢＮＭＭＭＬＭＭＭＮＬＬｾ . ._ ... , " ' -/I T. ·C I

ｾｲＭＭＭＭＭＭＭ｟｟｟｟Ｚ｟｟ＺＺ｟ＺＺ｟］Ｌ｟｟｟｟Ｌ｟｟｟｟Ｌ｟｟｟｟］Ｚ｟｟｟｟｟Ｚ｟ＭＭＭＮＬＭＭＭＭ｟

It

J

It 0

ｾＭｏＭＭＭＭＭＭＭ

...

］ＮＮＮＭＭ］ＢＢＢＢＧＭＮＮＮＮ｣ＺｯＮ］ＢＢＢＢＧｾ］］］］ＢＢＢＢＧ］ｾＢＢＢＢＧ］

(g) 6 FT DEPTH AS IN (a)

---

--...

}

ＭＭＭＭＭＭＭＭＢＧＭＭＭｾ ... -...-.---"""---- SAME

_.--.

' - ' ＮＭＮＮＮＮＮＮＭＭＮＭＭＮＭＮｾ

...,..."""""-'.-...._.--.-_

_

...

_

...

-

...

ＮＮＬＮｾＭＭＭＭＮＮＮＮＮＭＭＭ

---".--",-ｉ｜ｔＢｾ

J

J---,---,---ｉｾｯｲ

J_d-

ＮＮＮＭＮＭＮＢＢＢＭＭＧＧＧＧＧＧＧＧＧＧＧＧＧＧＧＧＧＧＧＧＧＧＧＧｾ］］］］］］］ＮＮＮＮＺｾ

NOV 68 DEC 68 JAN 69 FEB 69 MAR 69

FIGURE 5

TEMPERATURE DIFFERENCES BETWEEN CONTROL, SP6, AND STEEL POST, SPII, AND VARIOUS DISTANCES FROM SP II

(14)

II

I _CONTROL

AT GROUND SURFACE

l

5 FT

I

I FT DEPTH

1 4 F T

1 3 F T

!

6 FT

_1.

2 FT

611

4

1

9.7'

4'

9.7

1

• ｾ

1 ' .

I

-·1

·1

r • . - -

I

I .

'.

ｾＮＮＮ

I

｟Ｎｾｾ

"

.'.__•

1-·-

I

'"

·1

I

1....-.·

ｾＮ｟Ｌ

,

r-.-

_L

-j

i

I

ｊ｟ｬｊｾ

i-

1-

1---1

!

i

I

l l.l.l

I. .Ll_L

I

i l l

｟ｬｊＣｾ

1'1_1

I

i

ｾ

I

1/-1 - - - · - - _ .

I ·

.

-POSITION A

I

. ｾＭＭＭＭＭｾＭ

-1

-5

-4

-3

-2

-I

u

₀

0

.

LJ.J 0::

=>

I

-2

«

0:: LJ.J

3

Q.. ::E LJ.J I -

₄

5

6

7

SPI SP2 SP3 SP4 SP5 SP6 SP7

spa

SP9 SPIO SPII

FIGURE 6

AVERAGE TEMPERATURE DISTRIBUTION BASED ON DAILY MEANS FOR WINTER PERIOD

(18 NOV 1968 - 31 MAR 1969) AT VARIOUS DEPTH AND DISTANCES FROM STEEL POSTS

(15)

APR 69 MAR 69 MAX PENETRATION 1.72 FT 1.41 FT 0.98 FT 0.60FT 0.17 FT FEB 69 JAN 69 POSITION B POSITION

- - - - SPII STEEL POST ... SPIO 6IN. FROM POST - - - - SP9 I FT FROM POST . _ . - SP 82FT FROM POST - - - - SP7 4FT FROM POST

,1\

\ •.JV

II!

i \

-

i \

!

\J"

ｾＧｖｾ｜

_\'.

i '\

_I

, ""

_{. ,}

f

ｾ

\.

f:

i\

I

i

J

ｾｖＧ

d

'J

ＺｩｬｾＢ｜ｉ｜ＮＬｖｾ

i

V

II

i!

ｕＩｾ

\J'

A :: h ( , .' I\I , I Iii "

:flr"I'

_I

.'1

II_II _{, I....}, I _,

ｉＮｾ

\, \

ｉｾｉ It"

I II \'\ : , ,. I I " , \ I , IV I , \

\Ji

v-V"'!"

\!

ＧｶｾｍＮＮ

vol ,

r""

.i

.avi

\1 DEC 68 NOV 68 APR 69 MAR 69

I::

_:!1

｜ｾｾ

: I ;

,

'. I

\",

H,

_:,

ｉｾ

_:

:, J:

1\. :

_:

,'"

1\

l .. MAX PENETRATION 1.58 FT 1.15 FT O.58FT FEB 69 JAN 69 \.h. \

_-,

_:;

,

.

I, "I_{, I} _:'':

ｉｾＢｾ

_ｾ _I \ I I

ｾｬｾ

I ' ,/ I I f

I

I! I

V

r:'

I

ｾ

:;1 If, \

ＺｾＺ

I

ｾ

HI

ｉＡｾＬ

",-::1

ＺＺＺｉｾＺ

..

,,"i ...

'::;,

_{. .}

'V:::llE:

::.

.

_Y • : 2 I ...If ' . : ' ｾ I "'" : 1\

\: :,,'\ /-It ) :\t

1: ,.,it,: .!: '"

ft

ｾｾｉ｜ＺＮＯ

'.,

: l r

J

Ii

POSITION

--- SPI STEEL POST ... SP2 6 IN. FROM POST - - - - SP3 I FT FROM POST DEC 68 z :£ 40 ｾ 0-W o 20 3= 0 z ₀ en 0.2 0.4 0.6 0.8 ｾ 1.0 I.J...

-ｾ 1.2 w ::I:

b

1.4 ｾｾ 1.6 0 ｾ 1.8 0-w 0 2.0 2.2 2.4 2.6 2.8 NOV 68 FIGURE 7

POSITION OF O°C ISOTHERM ON STEEL POSTS AND IN THE GROUND AT VARIOUS LATERAL DISTANCES FROM POSTS

(16)

STEEL POST! POSITION B

I

SP9 SPIO SPII

spa

MAXIMUM SNOW DEPTH MAXIMUM SNOW DEPTH ..•,.•..•...••...•. 1··

ｾ

-

ｩｩｒｾｏｾＬ［ｾｾｾｅ

ｯｾｳｾＱｾｾｾｾｳ［ｩ［ﾷ｜｜Ｎ［［［ｾｳｬｊＺｾﾷﾷﾷ［ｾｪｩ［Ｉﾷ［［ｪＮｪｩｽ

ADVANCE

I I

l----POSITION OF THERMOCOUPLE

I

STRINGS

r

STEEL POST POSITION A

I

SPI SP2 SP3 SP4 SP7 I -u,

2.0

::I: ｾ

1.5

w c

1.0

3=

ｾ

0.5

(/')

o

0.5

2.5.

i i i i i i I -u,

z

o

i=

1.0 «

a::: I-w Z ｾ

1.5

l-(/') o a::: u,

2.0 2.5'

! I I I I ,

o

0.5 1.0

1.5 2.0 2.5

6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5

1.0 0.5

0 HORIZONTAL DISTANCE FROM STEEL POST, FT

FIGURE 8

SECTION VIEW OF MAXIMUM FROST PENETRATION AROUND STEEL POSTS

BASED ON ZERO DEGREE ISOTHERM