Requirements for the Installation of Soil Temperature Instruments at Knob Lake and Ross Bay

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Publisher’s version / Version de l'éditeur:

Technical Note (National Research Council of Canada. Division of Building Research), 1953-09-28

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Eden, W. J.

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DIVISION OF BUILDING RESEARCH

NATIONAL RESEARCH COUNCIL OF CANADA

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CAlL

NOTlE

No.

159

PREPARED FOR Qaebec North Shore & Labrador Railway

NOT FOR PUBLICATION

PREPARED BY

w.

J. Eden CHECKED BY C. B. Cral'1ford

FOR INTERNAL USE

APPROVED BY

Dr. N.B.' Hutcheon

DATE

28th Sept.,

1953.

SUBJECT ｒ･ｱｵｩｲｾｭＹｮｴｳ :ror the Installation of Soil

Temperature ｉｮｳｴｲｾｾ･ｮｴｳ at Knob Lake and Ross Bay

(1) Description of ｉｮｳｾｾｾｴｾＺ

The instruments consist of a mercury bulb which is buried at the desired depth in the soil. The bulb is connectied to a temperature indicator

(either a calibrated dial or a self-recording mechanism) by a stainless steel capillary tube. It is a mercury pressure operated system, the. temperature indicator beine; essentially a bourdon gauge.

The general requirements of the installation are that a pit be dug in the

ｾｳｏｩｬ so that the temperature bulbs may be placed at their required deptho The capillary tubes should be placed in a trench and protected by a crude trough made of light lumbero The temperature indicators should be housed in a water proof shelter.

(2) _-Location of the

_{_....}

ｉｮｳｴｾｾｾ･ｮｴｳＺ

--(a) Knob Lake: It is ｰｬｾｾ･､ to instal instruments in the Knob Lake

ｴｯｾｮｬｳｦｴ･Ｍｴｯｾ､･ｴ･ｲｭｩｮ･ the depth of frost penetration Ullder a roadway

partially clear of snOil in \<rinter, and under an area· lrri'l;h a moss al'ld loose snow cover. ｾｬ･ objective of this installation is to deter.uline a safe depth at which water and sewerage service lines must be

buried. The ｩｮｳＧｬ［ｲｬＮＮｵｾ･ｮｴｳ for this site consist of two three-pen recording thermometers and 2 dial thermometers. These instrunwnts are being supplied by the Division of Building Research, National Research Council.

(b) Railway cut section near Ross Bay: This ｩｮｳｴ｡ｬｾ｡ｴｩｯｮ is also aimed at the deternlinatlon of frost penetration but With a different objective o For maintenance plans of the railway the depth of frost penetration, the date in summer at which the frost will leave the ground (if it leaves the groIDld) should be ascertained. This

installation should represent typical conditions in a cut section, and ｾｯｲ convenience in reading it should be near a railway siding.

(c) String ｢ｯｾＡ･｡ near Ross BaX: In order to evaluate the effect of the insula:l:iing value of the s'l;ring bog cover this installation will be placed off the grade along an embanlonent section. It should represent typical string bog conditions and again be situated near a siding ｾｯｲ convenience in reading.

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2

-ｉｮｳｴｲｵｭｾｮｴｳ for installations (b) and (c) are being provided by the Quebeo North Shore and Labrador Railway Company through Mr. G. D.

Cree lman of the M. A. Hanna Company. .

(3) Pits for ｉｾｳｴ｡ｬｬ｡ｴｩｯｮＺ

For each installation the pit must be deep enough to allow the

ins·talling of the deepest tempe.rature bulb. Between the pit and the looation of the indicator a trench will be neoessary to bury the capillary tubes at a safe depth to provide protection from surface

traffic. Some rough lumber should be provided to construct a

crude trough as an additional protection for the capillary tubes. Since the capillary tubes are stiff and cannot be bent on a sharp radius, the trench from the pit to the indicator housing should be

dug to conform with these bending restriotions. The minimum radius

at whioh it is safe to. bend the capillary tubes is about 9ft •

The soil excavated from the pit if it consists of more than one soil

type must not be mixed. It will be necessary to backfill the pit

to conform as nearly as possible with the previous conditions. This

point is especially important where moss or muskeg form part of the

excavation. Thus, when excavating a pit, say in I' of muskeg,

2' of silt, and

3'

of till, separate piles should be made of muskeg,

silt'and till. The muskeg should be cut in large cubes or lumps

in order to preserve its natural structure.

With any inorganio soils it will be impossible to achieve the same soil density in backfilling as existed in the pitJrevious to

exoavation. To evaluate the effect of this faotor, in place

densities should be determined while the pit is being dug, and

again when backfilling. There should be a minimum of one density

determination for each soil layer or for each

3

feet of depth.

(a) Knob Lake: The installation pits at Knob Lake should

"15'19 10c'atEi'd to cover the following restriotions:

(1) To obtain frost penetration data under the centre of a'

road to a depth of

8'.

(2) To obtain frost penetration data under a moss and snow

cover area to a depth of

3'.

(3) Under the road the pit should be located to facilitate

instruments with capillary leads of

50'

in length, with

due allowance for the bending restrictions. This will

be the recorder type of instrument and will be housed in a heated building suoh as a garage or work shop.

,

(4) Under the moss and snO\-1 oover tw-o single bulb dial thermometers with 20' leads will be used.

(b) ｃｵｴｊ＿｟ｾｴｌｾｾｾｯｳｳ BaI: ｾｬｩｳ pit should be looated as

near to ｴｨｾ centre of the cut section as feasible. It is hoped to

measure soil temperatures to a depth of 10'. ｾｬ･ instrmuent's

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3

-(o) ｾｾｲｩｮｧ bog near Ross Baz: This pit should be located

off the railway grade in a string bog area. If ground water,

conditions permit, a temperature bulb will be placed at a depth

of

5'.

The instrument's oapillary leads for this installation

will be 301 _long.

(4) Instrument Housing:

(a) Knob Lake: For.good operation of the recorder type

instrmnent, it should be housed in an environment whioh is not

subjeoted to severe freezing temperatures. At low temperatures,

diffioulties are ･ｮ｣ｯｵｮｴ･ｲｾ､ with the ｩｮｫｾ used in the recorders. In addition, these instruments must be proteoted against rain

and snow. A garage or work shop which is heated to a reasonable

degree would form ｾｬｰｬ･ protection for these instruments. The

instruments oan be conveniently mounted on a wooden wall. (b&o) ｒｾｳｳ Bal: The dial thermometers should operate satisfactorily at temperature to minus 370_{F, the freezing point}

of meroury. These instruments should be protected from rain

and snow and hence require 'a weatherproof shelter. Each shelter should have a suitable back board for mounting these

instruments. The dial of each instrument will require about

one square foot of space eaoh. The baok board should be looated

away from the wall of the shelter in case the oapillary tube of the instrument enters the back of the indicator., Because temperatures lOwer than minus 37°F will probably occur during the Winter, the difficulty of the freezing of the instruments may be overcome by building a low shelter which can be banked

with moss and covered with SnOl'l during the period of extremely