VärETI) ID EE AN] ID E
Statens väg- och trafikinstitut (VTl) - Fack - 58101 Linköping Nr 30 - 1977 National Road & Traffic Research Institute - Fack : 58101 Linköping : Sweden
Report from participation in the second international symposium on cold regions engineering in Fairbanks, August 1976
Statens väg- och trafikinstitut (VTI) ' Fack ' 581 01 Linköping Nr 30 ' 1977 National Road &.Traffic Research Institute - Fack - 581 01 Linköping ' Sweden
Report from participation in the second
international symposium on cold regions
engineering in Fairbanks, August 1976
PREFACE
In August, 1976, the CREPA-committee, which consists of interested parties in North America, arranged an inter-national symposium on frost, called the Second Inter-national Symposium on Cold Regions Engineering in Fair-banks, Alaska.
As for Sweden, a representative from the National Swedish Road and Traffic Research Institute covered the symposium. In this report an account is given of the programme at thetsymposium.
Participation in the symposium has been made possible through contributions from Dow Chemical AB, Stockholm. Linköping January, 1977
TABLE OF CONTENTS
Report from Participation in the Secondenternational Symposium on Cold RegiOns Engineering in Fairbanks, August 1976
PREFACE
CREPA ORGANIZING COMMITTEE SPONSORS
TECHNICAL PROGRAM PROCEEDINGS
THEME OF THE SYMPOSIUM
SESSIONS AND PAPERS HELD AT THE SYMPOSIUM Heating and Cooling
Roads and Embankments Communications
Construction Instrumentation
Sanitary Pngineering and Pollution Control FOundations and
Soils-Energy
Pipelines and Offshore Structures Mining
Ice Engineering Building
TECHNICAL VISITS
PAPERS ON FROST INSULATION
VISIT TO THE USA CRREL PERMAFROST TUNNEL
VISIT TO ALYESKAN PIPELINE OTHER ACTIVITIES
Page
13 15 19
REPORT FROM PARTICIPATION IN THE SECOND INTERNATIONAL SYMPOSIUM ON COLD REGIONS ENGINEERING IN FAIRBANKS, AUGUST 1976
The second International Symposium on Cold Regions En-gineering is sponsored and presented by CREPA, the Cold Regions Engineers Professional Association. Following the highly successful first cold regions symposium at the Uni-versity of Alaska in 1970, it was hoped that additional symposia would be sponsored by one or another organization. However, no action was taken so a small group of engineers in and around the University of Alaska, Fairbanks organized CREPA for the primary purpose of sponsoring this second symposium.
l. CREPA ORGANIZING COMMITTEE
PREEIDENT Phil Johnson, U.S. Army Cold Regions
Re-search and Engineering Laboratory, Fort
Wainwright, Alaska
VICE PRESIDENT Dave Esch, Head, State Materials Labora-tory, Alaska Department of Highways,
Fair-banks, Alaska
SECRETARY/ John Burdick, Head, Department of Civil
TREASURER Engineering, University of Alaska,
Fair-banks, Alaska
MEMBER R Sage Murphy, Vice-President, Dames and
Moore, Denver, Colorado
2. SPONSORS
Engineering Department, University of Alaska
Alaska Section, American Society of Civil Engineers
Alaskan Projects Office, U.S. Army ColdRegions Research
and Engineering Laboratory Alaska Department of Highways
3.
TECHNICAL PROGRAM
Depending on the interest eXpressed and the number of papers received and accepted, sessions were scheduled in-the following areas:
Buildings and structures Communications and power Construction
Energy Mining
Pipelines and oil transportation Sanitary engineering
Soils and foundations Transportation
Tours and Technical Visits were arranged.
4. PROCEEDINGS
The compiled papers will be published by CREPA about one year after the symposium. One c0py will be sent to all registered participants and additional c0pies can be pur-chased.
5. THEME OF THE SYMPOSIUM
The theme of the 1976 symposium was Cold Regions Changes and Developments in the traditional engineering fields. Ice and permafrost were valid subjects in their engineering aspects but otherwise they are well covered through Special >organizations and international conferences and were deem-vphasized, Environmental protection and pollution control
were also deemphasized as they are often more closely re-lated to metaphysics than engineering. Energy, particularly
its use and conservation, has always been an area of
legi-timate engineering interest and energy-related papers were invited.
One subject of major interest in Alaska in 1976 was the Trans Alaskan Pipe Line, which was nearing completion at the time
the pumping
engineering feat. and applied
of the symposium. The pipeline, stations and the Valdez terminal,
including is a great Large amounts of engineering research engineering have gone into this project and were reported. Pipeline oriented and related papers were invited.
6.
The number of sessions were 12, were presented.
6.1
Chairman - Dr John Zarling, R R Gilpin
Terry McFadden J A C Kentfield, John E Cronin
6.2 Roads and
SESSIONS AND PAPERS HELD AT THE SYMPOSIUM
and more than 60 papers
Heating and Gooling
University of Alaska Ice Formation in Pipes
Protection from Damage to Utility Lines due to Freezing
A New High-Intensity, Pulsating, Combustion, Warm-Air Blower for Equipment Defrosting A Liquid Natural Convection Concept for Building Subgrade Cooling
Embankments
Chairman - Mr Woodrow Johansen, Alaska Department of Highways Rhode & Esch
'Berg & Quinn Condo, Clark & Wellman
_Johnson & Esch L C Miller
VTI MEDDELANDE 30
Kotzebue Airport Runway, Insulation over Permafrost
Use of Light Colored Surface to Reduce
Sea-sonal Thaw Penetration Beneath Embankments
Design and Construction of Synthetically
Insulated Pads in Alaskan Arctic
Investigation and Analysis of the Paxson Roadway Icing
for Frost Heave Areas Tested Rail-Road
A New Concept on the Alaska
6.3 Communications
Chairman - Mr Robert Merritt, University of Alaska Kenneth Kokjer
Hunsucker &
Merritt '
Robert Walp
6.4
Remote Area Data Communication by Satellite Radio Propogation Problems at High Latitudes State of Alaska Participation in Satellite Communication
Construction
Chairman - Mr Conrad Frank, GHEMM Haas, Alkire &
Bryan
Garfield & Mellor Haas, Alkire & Dingeldein
Rooney, Notting-ham & Davison Slipp & Plecnik William J Haslem J L Barthelmey M J Holland
6.5
Temperature, Snowfall & Earthwork Construc-tion
Permafrost Excavating Attachment for Heavy Bulldozers
Winter Earthwork Construction in Upper
Michigan '
A Driven H-Pile Foundation in Frozen Sands and Gravel
Low Temperature Effects on High Strength Bolted Steel Connections
Army DevelOpmental Testing in the Arctic Construction of a Surface-Flooded Ice Wharf Cold Weather Masonry Construction
Instrumentation
Chairman - Mr Robert Merritt, University of Alaska DaVid Esch
JimaMovius
Dick Siegrist
VTI MEDDELANDE 30
Ground Temperature Instrumentation Systems
of the Alaska Department of Highways
InstrumentatiOn of Test Sites under Arctic
Conditionsp '
6.6 Sanitary Engineering and Pollution Control Chairman - Mr Douglas Lowery, Alaska Department of Environmental
Smith & Given Reed, Sletten & Uiga Conrad Christian-son H J Coutts Terry McFadden 6.7 Conservation
Evaluation of Northern Estended Aera-tion Sewage Treatment Plants
Land Treatment of Wastewaters for Alaska Cold Climate Aerated Lagoons
Experiences with a Snow Melter Water Supply System
Ice Fog Suppression Using Mono-molecular Chemical Films on Power Plant Cooling Ponds
FoundationS'and'Soils
Chairman - Mr Ronald Abbott, Shannon and Wilson Sherif,
Ishi-bashi & Ding Arvind Phukan McRoberts & Nixon
Jon A Bendz Rice & Ferris Ersoy & Togrol
Harry Lee
6.8 Energy
Frost-Heave Potential of Silty Sands Simplified Approach to Slope Stability in Thawing Soils
Extensions to Thawing Slope Stability Theory
Pile Installation Methods in Permafrost Some Laboratory Tests on Creep of Steel Piling in Frozen Ground
The Factors Affecting the Shear Strength of Frozen Soil
Permafrost Considerations, Anchorage
Chairman - Dr Terry McFadden, USACRREL C_Bettignies
E F Rice Paul.B Crews
VTI MEDDELANDE 30
Energy Conservation in Arctic Regions
Energy Conservation in Space Heating* Heating the Fairbanks, Alaska Wastewater Treatment Facility with a Heat Pump and TreatedyEffluent
Philip R Johnson Measuring Unmetered Steam Use with a Condensate Pump Cycle Counter
Carol E Lewis The Utilization of Waste Heat in
Agri-business Development: A Systems Approach
John Houk The Use of Waste Heat for Salmon Agriculture
D H Dinkel & Potential for Production of Intensively
Cul-Lewis _ tured CrOps in Alaska using Geothermal or
Waste Heat Sources
6.9 Pipelines and Offshore Structures
Chairman - Mr Wayne Tobiasson, USACRREL
Donald E Keyes Ice and Snow for Roads, Airfields, Bridges
and Workpads
James McDougall The Beaufort Sea Project Surface Facilities
W R Petri Environmental Safe Highway-Pipeline for
Tundra and Permafrost Regions
Swamidas & Reddy Dynamic Response to Ice Forces: The Offshore
MonOpod System proposed for the Canadian
Beaufort Sea '
6.10 Mining
Chairman - Dr Ernest Wolff, University of Alaska
McClusker & Development of Arctic Oil & Gaz by Tunnelling
Tarkoy
-Douglas W Bent Mining Operations at Whitehorse COpper Mines
Ltd '
Paul Clark
Open Pit Mining in a Northern Environment
Paul Metz A Comparison of U S and Canadian Mining
In-dustry with Emphasis on the Yukon and Alaska
6.11 Ice Engineering
Chairman - Dr Wm Sackinger, University of Alaska
Roscoe E Perham Some Economic Benefits of Ice Booms
Johnson, Burdick, Yukon River Breakup, 1976 Esch, McFadden,
Osterkamp & Zarling
Reddy, Swamidas Viscoelastic Finite-Element Analysis of
& El-Tahan Reinf Floating Offshore Ice Platforms
6.12 Building
Chairman - Dr E F Rice, University of Alaska
Ledbetter & Habitability Guidelines for Design of Cold
Flanders Regions Buildings
Wayne Tobiasson The New Corps of Engineers Pamphlet "Design
Data for Construction in Alaska"
Mark Fryer Some Life Cost Construction in Building Design
Andersen & Arco Prudhoe Bay Operations Center
Crittenden
Flanders, Tobias- Reinsulating Old Wood Frame Building with
son & Gropp Urea Formaldehyde Foam
John P Zarling Thermal Performance of Windows
Tobiasson & Detecting Moisture in Roof Insulation with
Korhonen a Hand-Held Infrared Camera
F Lawrence Ben- Temporary Enclosures and Heating in COld
nett Regions Construction
7. TECHNICAL VISITS
Technical Visits were arranged to the following sites: The Fox permafrost tunnel
Gilmore Satellite tracking site
Alyeska pipeline and/or pump statiOn New Fairbanks sewage treatment facility The Fairbanks flood control project
8. PAPERS ON FROST INSULATION
Kotzebue Airport Runway Insulation OVer Permafrost
by James J Rhode, Alaska Division of Aviation, Anchorage, Alaska, David C Esch, Alaska Department of Highways, College, Alaska, U S A
In 1969, a 1900 foot length of the East-West Landing Strip at the Kotzebue Airport was reconstructed using a four inch
thickness of "Styrofoam" insulation board at a depth of
three feet, to prevent thawing at the underlying permafrost and resultant settlements of the runway. The runway was sub-sequently paved with a hot mixed asphalt concrete surfacing. A system of 24 thermacouples was installed to observe
subsur-face temperaturestltimainsulated area and also, for compari-son purposes, beneath an uninsulated taxiway. Continous moni-toring was done on all thermacouples by use of a 24 point re-corder.
As there was a shortage of gravel in that part of the cOun-try, heat insulation of the road with plastic foam was
thought to be economical. By designing the heat insulated base, gravel underneath the plastic boards could be con-sidered in calculations. In permafrost areas thawing index is critical. The thawing index as 0.7 of the freeZing index was proposed.
Use of a Lightacolored SurfaCe toReduce Seasonal Thaw PenetratiOn beneath Embankments On PermafroSt
R L Berg and W F Quinn, U.S. Army Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire U S A The construction of embankments on permafrost, particularly in regions where the mean ground temperature is close to
the melting point, usually results in melting of the
perma-frost which may cause settlement of the embankment. The depth of melting (thaw penetration) is considerably
in-creased shOuld the surface of the embankment be cOvered
with a bituminous pavement. This increased melting results from greater absorption of solar radiation by the dark
sur-face. A light-colored surface (white traffic paint) has been
used on the asphalt runway at Thule AB, Greenland (a
cold permafrost site) and on highway test sections near Fairbanks, Alaska (a warm permafrost site). The concept is being considered in the selection of surfacing mate-rial for some embankments on the Chena River Flood Con-trol project.
At Thule Ab, the white painted portion of the runway and taxiways typically thaws to maximum depths of 2,5 to 3 feet (0.75 to 0.91 m) whereas the natural black asphaltic concrete pavements thaw to about 7 to 8 feet (2.13 to 2.44 m). The design air thawing index at Thule is 1217 OF-days (676 OC-days) and the average is 637 OF-days
(354 OC-days). At a USACRREL Highway Test Section site near Fairbanks, the seasonal thaw depth beneath a white painted roadway varied from about 7,5 ft to 8,5 ft (2.2 to 2.51 m) whereas the thaw depth beneath the natural dark asphalt concrete section was about 11.3 ft (3.44 m). These observations covered the period from 1966 through 1971. Essentially no settlement was observed in the white painted highway section whereas about 0.7 ft (0.21 m) was measured in the natural aspahltic concrete section. The design thawing index in Fairbanks is 3807 OF--days (2115 OC-days) and the mean is 3370 OFjdays (1872 OC-days).
It is possible to combine a heat insulated road base with a white or at least a bright paVement Surface and in this way reducing the heat radiation from the surface. This
will be a method for reducing the thickness of the
insula-ting layer and also for reducing the risk of early autumn icing. At a test area at the National Swedish Road and Traffic Research Institute it is planned to investigate
the role of different brightness of the pavement in order to influence the surface temperature.
The New Corps of Engineers Pamphlet "Design Data for Construction in Alaska
Wayne TobiaSson, U.S. Army Cold Regions Research and
Engineering Laboratory, Hanover, New Hampshire U S A
10
Working cooperatively over the past several years, CRREL and the Alaska District have develOped a pamphlet to aid designers in Alaska. The pamphlet, which as of the wri-ting is in draft form but should be cOmpleted by August, 1976, contains tabulations of temperature, precipitation, heating degree days, together with wind, snow and seismic load information for over 300 locations in Alaska. The accompanying text describes how to properly use the tabu-lated information. The pamphlet should be an important design aid for engineers working in the 49th state.
With data from this pamphlet it is possible to make quali-fied designs of frostinsulated structures in Alaska. It can be compared with our statistics of temperature (free-zing index), precipitation cava, which.we already have in the northern European countries.
Design and construCtiOn of'Synthetically Insulated Gravel Pads in the Alaskan Arctic
by James H Willman, PE, R & M Engineering, Inc., Fairbanks, Alaska
Edwin S Clarke, P E, Consulting Engineer, Fairbanks, Alaska Albert C Condo, Alyeska Pipeline Service Company, Anchorage, Alaska
ConstructiOn of the Trans Alaska Pipeline System required the construction of an embankment paralleling the pipeline to permit Operation of pipeline construction equipment and
limit terrain disturbance. About seventy miles of the work
pad, north of the Brooks Range utilized synthetic foam
in-sulation to prevent thawing of the underlying ice-rich
soils. The insulted work pad was designed with a 1 1/2
to 3 1/2 inches thickneSs of polyStyrene foam insulation
underlain with a six inch bedding and a minimum of sixteen inches of well graded overlay. See photo page
12-As construction commenced, it became apparent that
suffi-cient gravel sources for bedding and trafficking
ll
cations were not suitably located. A test program showed that a suitable surface on which to place the insulation could be prepared without placing the bedding and that a 15 to 40 percent increase in insulation thickness would permit the use of coarse, poorly graded gravel or highly weathered rock as a traffic course. Consequently, a field design change was made to eliminate the bedding require-ment and place the insulation directly on the leveled tund-ra. Techniques were also developed to eliminate the need for pinning the insulation. Insulated culvert bedding and low water crossings were used to prevent thawing of ice-rich soils beneath cross drainages.
For the areas where synthetic insulationwas used in the
work pad, a thermally equivalent embankment that utilized only gravel as the insulating material would be five to seven feet in thickness. Because the synthetically in-sulated work pad required an average embankment of only aboht 24 inches, significant reductions in material bor-row quantities were realized, compared to an all gravel design. These reductions resulted in a reduced distur-bance to the terrain caused by the development of mate-rial sites, a more rapid completion of the work pad
con-struction and concon-struction cost savings for the project.
V T I M E D D E L A N D E 3 0
A MT_ 56,.. Jøbhx øxi c é 6A ?ii »Azzálg'od'ä'Nlt'hi '1" / .V ; z. .- 49,
Photo- Finished Segment of Insulated Work Pad.
13
9. VISIT TO THE USA CRREL PERMAFROST TUNNEL
The U.S. Army Cold Regions Research and Engineering Laboratory (USA CRREL) permafrost tunnel is located at Fox, 10 miles north of Fairbanks, Alaska along the Steese Highway.
The tunnel was excavated for the purpose of investi-gating various commercial tunneling equipment in the frozen silts and gravels. The frozen silts (muck) is relatively easy to excavate, the frozen gravels are very difficult to excavate using machines. Drilling and blasting proved to be better. The tunnel is cut in the near vertical muck (reworked silt mixed with organic material) cliff on the southeast side of the placer mi-ning Operations at Fox. The muck originally filled the whole valley, covering the gold bearing gravel below. The muck was removed, usually by hydraulic means, and
the gravel on t0p of bedrock washed for gold. The muck
escarpment then represents the edge of the placer Ope-rations.
The possible magnitude of the Engineering Problems with ice-rich permafrost are exposed in the tunnel. The silt
size material (such as muck) is the source of the
majori-ty of problems related to permafrost. Silt size material
have the best "wicking action" of soils. Upon freezing,'
(both seasonal and permafrost) water Can migrate to the
freezing surface thus increasing the total water content in a body of silt mannyld. The growth of Taber iCe and ice wedges show this. The problems with permafrost will
occur if the material (silt) is permitted to thaw. The
water generated cannot move downward (the ice below pre-vents this) thus increasing the moisture content in the thawed zone often to the point-of soup. The bearing capa-city of the soil is greatly reduced (to almost non-exis-tent). The melting of large volumes of ice also induces settlement of the soil surface with sometimes less than -desirable consequences. The effects of melting of
14
frost on roads, railroads, houses and even farming can be disastrous. Remember, thawing of permafrost can take place if the ground Cover is removed or disturbed. The permanently frozen gravels exposed in the tunnel pre-sent quite another picture of a material in a perma-frost condition. There is only interstitial ice pre; sent, and the gravels appear to have grain to grain contact. No ice wedges or other bodies of ice occur in the gravels. Ice wedges seem to truncate when they reach the gravels. Thawing of clean gravels like those found in the tunnel would then cause little or no settlement of the surface, no engineering problems upong thawing so to speak. But remember, Excavation of permafrost gravel is a real engineering problem.
The smell in the tunnel from the decaying organic matter in the muck. The muck is reworked silt with intermixed organic material. The muck was deposited unfrozen, and decay of the organic material was free to take place. It is believed that the muck may have gone through se-veral cycles of freezing and thawing, decay taking place in the thawed stage. The dugg. Due to sublimation of the ice, dust is present everywhere, a thick layer is on the floor of the tunnel. The sublimation has also made the ice wedges retreat. The Frost. The frost cryStals cover large areas of the ceiling. This is a function of bringing moisture in from the outside. creep and Subsidence? The gravel exhibit spectacular creep and subsidence. This can
be observed by the poles and beams installed in the
cham-ber excavated in the gravel. The creep rate is temperature dependent. Large rates are found in "warm" permafrost.
15
Ice wedge distribution and relative position of radiocarbon dates (years) from the tunnel Section.
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0lO. VISIT TO ALYESKAN PIPELINE
The new 800-mile trans Alaska pipeline is being built
for one purpose: to make the 9.6 billion barrel oil
re-serves at Prudhoe Bay, Alaska, available to U.S. indust-ry and consumers.
Initially, 1.2 million barrels of oil a day will be
trans-ported through the line from Prudhoe Bay to Valdez, Alaska,
for shipment by tanker to West Coast ports. At capacity, the total will reach 2 million barrels a day.
This project, the largest privately funded construction
effort in history, is being built by the Alyeska Pipeline
Service Company, formed by eight companies - The Amerade
Hess Corporation, ARCO Pipe Line Company, SOHIO Pipe Line
Company, Exxon Pipeline Company, Mobil Alaska Pipeline
Company, Phillips Petroleum Company, Union Alaska Pipeline
Company and BP Pipelines, Inc.
The oil pipeline system is being developed in two phases. The first phase, scheduled to completion in mid-1977, in-cludes completion of a new all-weather highway from the Yukon River to Prudhoe Bay, construction of a 48-inch steel VTI MEDDELANDE 30_
16
pipeline from Prudhoe Bay to Valdez, building of eight pump stations along the route and develOpment of oil storage and tanker loading facilities at Valdez. See page 20.
Four additional pipeline pump stations along the route and more oil storage and tanker docking facilities at Valdez are planned in the final phase.
The new pipeline will bring oil across some of the most rugged terrain in North America, but it will have an im-pact on very little Alaska land. On completion, the line
will ocCupy only 12 square miles of the state's 586,000
square miles. Construction will have a temporary impact on an additional 50 to 60 square miles.
Starting in the Arctic plains of Prudhoe Bay with its annual rainfall of only 6 inches, the pipeline climbs 4.800 feet over Dietrich Pass in the Brocks Range, cros-ses the Yukon River, climbs 3.300 feet over the Alaska. Range and then over Thompson Pass in the Chugach
Moun-tains before reaching the ice-free port of Valdez. Temperature along the route range from the 903 in the summer, when the Alaska sun remains up all day, to 80
degrees below zero Fahrenheit in the day-long darkneSs of the northern Alaska winter.
Soil and seismic conditions along the route are also
un-usualiijuch of the pipeline route is.underlain with per» mafrost - penmanently frozen soil - in some places
hund-reds of feet thick. In the coldest regions, the permafrost
is Covered with a fragile mat of delicate vegetation called'
tundra, easily damaged when in a melted state in summer.
Special construction designs_and techniques were developed to protect all such sensitive areas.
Earthquakes also pose special pipeline design and
17
tion problems. The Alaska earthquake of 1964, which reached the highest magnitude ever recorded, 8,5 on the Richter scale, was centered in Prince William Sound. The ground motion produced by a quake app-roaChing that magnitude could create unusual bending, tension and compression stresses on the pipeline, as well as tend to damage pump station and terminal
faci-lities. An additional threat to the terminal could come from seismic sea waves caused by possible landslides along Valdez Arm.
To withstand these forces, every aspect of the pipeline
system - pipe, pump stations and terminal - has been
de-signed to withstand a contingency level earthquake at any particular point along the line. Seismologists deem the occurrence of such an earthquake in the Vicinity of the pipeline as very unlikely during the life of the line, and deem this event ever being exceeded as even leSs likely. The advanced design of the pipeline control system will provide the capability to maintain control of the pipeline and facilities during and after a contingency level earthquake. The line and facilities have been designed to operate without interruption during a quake of one-half contingency level. Terminal facilities at Valdez are being
built largely on bedrock and well above the level of any
potential seismic sea wave.
Planning for the pipeline began in 1968 after the discovery of oil at Prudhoe Bay. While legislative, environmental and court hearings were being conducted in Alaska and Washing-ton D.C. pipeline enigneers and scientists carried out de-tailed and extenSive environmental-and design studies on all phases of the system.
Pipe to be used in the pipeline underwent rigorous labora-tory tests. Special soil rehabilitation programs were devee loped and proven. Extensive rock and soil Samples were taken all along the route. Scientists and engineers prepared a
detailed Comparative analysis of resource values and possible riSks for the entire system.
18
In addition, scientific Specialists conducted specific studies along the route in biology, botany, agronomy, zoology, geology, seismology, archeology, marine bio-logy and oceanography.
Construction of the pipeline system began with work on the pipeline road, north of the Yukon River, in April 1974. President Nixon had signed measures authorizing construction in November 1973. Federal and state per-mits were issued shortly thereafter.
Work on the road and preparation of pump station and terminal sites began first. Construction plans called for the actual pipeline, stations, terminal facilities and permanent communications systems to follow.
All the construction work has been subjected to a higher level of inspection than ever used on any oil pipeline project before. In addition to undergoing in-spections by federal and state agencies, pipeline work also has been subjected to a two-level inSpection pro-cedure adapted from the nuclear power industry. In this system, work of the traditional quality control inspec-tor is also reviewed by an independent quality assurance auditor charged with seeing that all inspections and work are performed pr0perly,
Operational and contingency plans also have been developed for operation and management of the system. In-depth,:pre-planned programs for responding to any chtingencies have
already been prepared.
The Operating communication network for the system will be built around.a new microáwave network, the first to
cross Alaska from norht to south. The micro-ane system
will be backed up with earth station links to a satellite in orbit above the equator.
ll. OTHER ACTIVITIES
At the symposium there were many opportunities of discussing with researchers and engineers in the frost activity field and with special reference to frost damage and frost protection. The journey was extended to other places such as Quebec and Ottawa. In the last-mentioned city a visit was paid to NRC, Division of Building Research, Geo-technical Division, where one t0pic of discussion was the Symposium on frost action in soils, which is to be held in Luleå, Sweden, in February, 1977.
VTI MEDDELANDE 30
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VTI MEDDELANDE 30
whereverthetrans Alaska pipeline is being erected over marginal permafrost. special thermal devices known as heat pipes are being installed to maintain the permafrost in a stable condition around vertical pipeline support members'
ln marginal permafrost. where frozen soil temperatures are nearfreezing. surface
disturbances or natural climate changes can melt the permafrost and cause progressive thawing of the subsoil and thaw settlement.
The heat pipes prevent both" settlement ofthe supports or their jacking." a heaving and lifting
action caused byfreeze-thaw cycling in the soil.
Typical Thermal Support With Two Heat Pipes
The self-operating heat pipes act to reduce soil
temperatures around supports wherever the air temperature drops below the temperature of the ground. The pipes operate only when the air temperature is less than the temperature of the soil.
The heat pipe is a natural convection. two-phase heat transfer loop which transfers heat by
vaporization and condensation within a closed
system. lt consists of a sealed tube, charged
with a working fluid. which functions as a
two-phase system at Operating temperatures.
Heat (from thevs'oil) entering the lower end of the
tube causes the fluid to boil. The vapor travels to Plan View
21
the upper, radiator end of the tube in the air. where it condenses on the cooler surface, releasing energy. The condensate then returns to the lowerend of the tube as a film along the tube wall. lnternal grooves are added in the evaporator to provide betterfilm distribution.
A radiator is installed on the condenser section to improve the heat transfer from the heat pipe to the atmosphere.
The utilization of the heat pipes in marginal. permafrostconditions has resulted in reducing
the below ground vertical support lengths and allowing greater loadebearing capacities. Cross Section of Aluminum Radiator
rH--- 3%: W.T. x 11/2 l.D.
6 Steel Jacket 188" 20 Fins
F_-. Aluminum. . Equally § I Radiator Spaced 4, and 2 10 9" 5 W Cross Sectlon '980 i i' ä r r ø / l i 1 C Fins.125" 1 H r % to_.062" ? i j thick E
TI å"* \: :NN, ,co- °--°"- Pooncrete Plug
,4 V* ' Variable v 1 1 : Support 6 /v /4 W.T. X 1/2 LD. Stick-Up : Ground \ ' Sudace \ x x : Pipe: .
N . Mechanical iow-tempered steel \ tubing; 1V2 inch inside diameter; V4 6
: Heat pipes (2" OD.) - %Tnch wall'thickness(W.T.); 31 to-66
N footlengths. N _ . n Radiators:
ä _5:13:2an Off' 1 _ Extruded aluminum; 10.9inches in
| \*N Touch; ng; Geometry of Typical- diameter; 4 and 6 foot lengths.
i ' , - Retrigerant: Variable ; . . Th? malpue'nsmuanon Anhydrous ammonia.
Support vemca' 3 0,, 6,. Lite:
Embedment gr 5.5.3' Support ' *i l*- i 30 years.
Typically 25' x :2- " Members j _ Replaceabiltty:
. : 5555:: 8 ,l F." |nsu|ation 'Radiator sectionofdefective heat
3 O' ' . - pipe will be removed and a smaller
: :13" (Net sa'turated) - JaCkçt . i Radlafor diameter heatpipe will beinserted \ P'pe Il ' 6" inside the existing pipe.
: 1?" '_L Assembly:
\ _1_ i _ Fins are pressed on pipeassemblies
N * _ T in the field and inserted two at a time
: i 18"_q l ._ . in support members»
N '5 i l 8'10 25' ContractOr: _
t 4 I . McDonnell DOuglas'Corporation,
? Variable hifi* F Vemca' TotalUnits:
l 65"_30" på; ' " Support 112.000for56.000vertica|support
L * I v - - - : ._. i / 'W Vi 4V . 1! , i / it\ ,7,7 members. (2to each member)
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?Vill .1" 975 Headquarters: 1835 South Bragaw Street Anchorage. Alaska 99504 O
