Deformations of a highway embankment on degraded permafrost

uildings and pipelines, airport runways, rail beds, and<strong>highway</strong> sub-bases, cuts and fills.DiscontinuousPermafrostWinnipegPR391ThompsonChurchillContinuouspermafrost-1˚CFigure 1. Location <strong>of</strong> test site and permafrost in Manitoba,CanadaBecause the ice lenses are typically irregular inthickness and extent, out-migration <strong>of</strong> water <strong>of</strong>tenproduces differential settlements, lateral spreading, andreduced stability that lead to serviceability issues. .Typically, this thaw settlement is irregular (Hinkel et al.2003).Although the permafrost regions in northern Canadaare not heavily populated, their economic importance hasincreased substantially in recent decades owing to thepresence <strong>of</strong> mineral, petrocarbon and hydroelectricresources. Thawing <strong>of</strong> summer ice in the Arctic Oceancan be expected to lead to additional shipping into the port<strong>of</strong> Churchill. New roads and railways will have to beconstructed into northern Manitoba and Nunavut oversoils with engineering properties that may degrade withclimate change and land-use. Design, construction, andmaintenance <strong>of</strong> this new infrastructure will have to takeaccount <strong>of</strong> future warming (Hinkel et al. 2003).Figure 1 shows that Manitoba has discontinuouspermafrost north <strong>of</strong> the isotherm for a current meanannual air temperature <strong>of</strong> about 0ºC (about 2500ºC-days<strong>of</strong> frost). The permafrost becomes continuous furthernorth near the Hudson Bay coast.Construction in permafrost regions requires specialtechniques where soil pr<strong>of</strong>iles contain ice lenses.Disturbance <strong>of</strong> existing ground cover can change theenergy regime (Nelson and Outcalt, 1982). This <strong>of</strong>tenleads to thawing <strong>of</strong> underlying ice-rich permafrost andsubsidence <strong>of</strong> the road bed. <strong>Deformations</strong> can besufficiently large that the road becomes inoperable.Several methods are currently used to prevent orminimize thawing <strong>of</strong> permafrost and development <strong>of</strong>thermokarst. These include above-ground construction,use <strong>of</strong> thermosyphons, and buildings on piles or gravelpads above original ground level.Highway construction in northern Canada followsbroadly similar practices to those in warmer regions. Fillsgenerally have high thermal conductivity, leading to heattransfer into underlying layers and thawing <strong>of</strong> previouslyfrozen foundation soil (Batenipour et al. 2009b). Asphaltsurfacing absorbs heat from the sun and transfers it to the<strong>embankment</strong>. Generally, degradation <strong>of</strong> permafrostbegins at the toe <strong>of</strong> <strong>embankment</strong>s and extends laterbeneath the centre. Melting reduces strength andincreases pore water pressures when the hydraulicconductivity <strong>of</strong> the foundation soil is low. This leads todifferential settlements, lateral spreading, and instability.In order to improve local design and maintenanceprocedures, Manitoba Infrastructure and Transportation(MIT) and the University <strong>of</strong> Manitoba (UM) arecollaborating on several projects that involve fieldinstrumentation, laboratory testing and numericalmodeling. This paper reports work on a project onProvincial Road PR391, about 18 km northwest <strong>of</strong>Thompson, Manitoba (Figure 1). This is the only roadconnecting Thompson to northern mining towns,hydroelectric generating stations, and first Nationscommunities in north-western Manitoba. The site is in aregion <strong>of</strong> discontinuous permafrost.2 GEOTECHNICAL SITE INVESTIGATIONS ANDFIELD INSTRUMENTATIONS2.1 Site InvestigationThe PR391 was initially constructed as a compactedearthen road on discontinuous permafrost in the mid-1960s and then converted to a gravel road in the early1970s. In the early 1980s, it was upgraded with abituminous pavement surface. Since construction,changes in heat transfer have melted permafrost that hadbeen detected earlier, particularly under <strong>embankment</strong>s.Thawing led to large ongoing irregular deformations anddangerous traffic issues.Responses by MIT included construction <strong>of</strong> stabilizingberms and insulating peat berms beside the project<strong>embankment</strong> in the early 1990s. Over some years, theberms settled into the foundation soil and essentiallydisappeared. They currently provide no additional supportto the original <strong>embankment</strong>. Regular maintenance hasadded several metres <strong>of</strong> gravel fill since initialconstruction. Where extra maintenance is required, thewearing surface has been returned to gravel from asphalt:the asphalt pavement from the early 1980s has not beenreplaced.In 1991, drilling encountered frozen soil at depths from1.9m to 10.5m below the toe <strong>of</strong> the <strong>embankment</strong>. Laterdrilling in 2005, detected frozen soil at depths from 4.6mto 10.7m. Perhaps surprisingly, no frozen soil wasidentified in a recent drilling program in late 2008 usingcontinuous flight, solid stem augers. A later section willshow no sub-zero temperatures below the active surfacelayer. Considerable maintenance was required at the site.Records outlining maintenance procedures and annualapplication <strong>of</strong> gravel are unavailable.Figure 2 is the authors’ interpretation <strong>of</strong> the results <strong>of</strong>the site investigation at PR391 in 2008. The investigation

involved two cross-sections, one <strong>of</strong> which was designatedas ‘stable’ and the other as ‘unstable’. The stable sectionis only about 2m high (Figure 2a) and has not deformedsignificantly. The unstable section is also about 2m highabove the surrounding natural ground. It has settledconsiderably and now contains about 5m - 6m <strong>of</strong> gravel(Figure 2b). The gravel is partly from the originalconstruction and partly from ongoing re-grading. The‘zero’ depth in Figure 2 and in subsequent figures isreferenced to the level <strong>of</strong> the original ground surface and<strong>of</strong> the surrounding undisturbed land.near the toe. At the mid-slope, the soil is primarily silt toclayey silt. The toe <strong>of</strong> the unstable section consists <strong>of</strong>1.0m <strong>of</strong> clayey peat-silt, 1.0m <strong>of</strong> fine gravel, followed by alayer <strong>of</strong> highly plastic clay. This clay is firm, brown, siltyclay at upper levels and becomes very s<strong>of</strong>t and grey to adepth approaching 18m. The mid-slope <strong>of</strong> the unstablesection consists <strong>of</strong> almost 2.0m <strong>of</strong> clayey peat-silt, over2.0m <strong>of</strong> loose fine gravel, followed by firm brown silty claythat transitions to grey and s<strong>of</strong>t clay. Both sections areunderlain by gneissic bedrock. The surrounding area ispoorly drained - there is free-standing water withinapproximately 20m <strong>of</strong> the <strong>embankment</strong> toe when snow isnot present.2.2 InstrumentationClusters <strong>of</strong> instruments were installed at the shoulder,mid-slope and toe <strong>of</strong> both the stable and unstable sections(Figure 3). They include thermistor strings at 1m intervals,vibrating wire piezometers and standpipes, surfacesettlement plates, slope inclinometers, and lateraldisplacement extensometers at the toe <strong>of</strong> the<strong>embankment</strong>. The piezometers and standpipes wereused to identify possible upwards or downwards hydraulicgradients.Temperatures have been collected during two wintercycles. Readings were taken monthly on a dataacquisition system and downloaded manually. Telephoneaccess was not available at reasonable cost at therelatively remote site.3 DATA FROM FIELD INSTRUMENTATIONFollowing sections analyse the results <strong>of</strong> the fieldobservations. The data include surveyed results from thesurface settlement plates, displacements measured byinclinometers and horizontal extensometers, pore waterpressures, and monthly temperatures from the thermistorstrings. Inserts in following figures show the positions <strong>of</strong>the instruments for which results are being reported.3.1 Movements measured by surface settlement platesFigure 2. a) stable section; b) unstable sectionThe terms stable and unstable are here used in thesense <strong>of</strong> a serviceability limit state and not an ultimatelimit state. There are no indications <strong>of</strong> deep-seatedrotational movements.Boreholes were drilled at the mid-slope and toe <strong>of</strong>each section to examine the stratigraphy, collect samplesfor laboratory testing, and install instruments to record thebehaviour <strong>of</strong> the foundation soils over several years.Batenipour et al. (2009a, b and 2010) provided additionalinformation about site characterization, instrumentationand material properties. This paper provides informationon two full years <strong>of</strong> field measurements.Figure 2 shows that soil conditions below the originalground level (at depth ‘0’ in the figure) at the two sectionsare considerably different. The stable section consists <strong>of</strong>approximately 4.0m <strong>of</strong> s<strong>of</strong>t-to-firm clayey silt/silty clay withpeat intrusions that vary from thin stratifications to pocketsFigures 4 and 5 show displacements <strong>of</strong> surface settlementplates in metres in both the stable and unstable sectionsat the shoulder <strong>of</strong> the road, at mid-slope, and at the toe <strong>of</strong>the <strong>embankment</strong>s. Vertical movements are shown aselevation changes in Figure 4, and horizontal (lateral)movements perpendicular to the centreline <strong>of</strong> the road inFigure 5.Figures 4a, 4b, and 4c show the vertical movements atthe shoulder, mid-slope and toe <strong>of</strong> the two sections. Bothshow seasonal movements that are largely, but notcompletely recoverable. Because <strong>of</strong> the gravel in the<strong>embankment</strong>, the seasonal movements at the shoulderare small. There appears to be little cumulativemovement at the shoulder <strong>of</strong> the stable section. Incontrast, there has been about 0.15m <strong>of</strong> settlement at theshoulder <strong>of</strong> the unstable section. Seasonal heaves arelarger at mid-slope, and larger again at the toe. Again thestable section shows little cumulative movement, while

28-Mar-0906-Jul-0914-Oct-0922-Jan-1002-May-1010-Aug-1018-Nov-1026-Feb-11Vertical (m)Depth (m)28-Mar-0906-Jul-0914-Oct-0922-Jan-1002-May-1010-Aug-1018-Nov-1026-Feb-11Vertical (m)Depth (m)06-Jul-0914-Oct-0922-Jan-1002-May-1010-Aug-1018-Nov-1026-Feb-11Vertical (m)there is about 0.08m <strong>of</strong> cumulative settlement at midslopeand 0.04m at the toe.The lateral movements at the ground surface (againfrom the settlement plates) in Figures 5a, 5b, and 5c showsomewhat similar trends, though seasonal effects areperhaps only apparent at the toes <strong>of</strong> the <strong>embankment</strong>s.Again, the stable section did not move much in the two040123415114.414.41 2 2 31 2 31 2 3 4 4 5 6 7a) -0.151 2 3 4 5 6 71 - SurfaceSettlement2 - DeepSettlement3 - Thermistors4 - Stand Pipe5 - SlopeInclinometer6 - Piezometers7 - ExtensometerThe toe <strong>of</strong> the <strong>embankment</strong> shows the highest amount <strong>of</strong>frost-heave during the freezing season while the shouldershows almost no frost heave, probably due to the gravelfill on the shoulder. Gravel can be considered to be anon-frost susceptible material (Koyama and Sasaki 1967).It drains freely by gravity and does not lead to upwardmovement <strong>of</strong> capillary moisture.Elevation0.050.00-0.05-0.100.100.050.00-0.05-0.10SurfaceSettlement14.414.4SurfaceSettlementa)Date Elevationb)StableUnstableStableUnstable8b)0.100.050.00StableUnstableElevation Date-0.0514.4SurfaceSettlementc)20-0.10Figure 3. Instrumentation at a) stable section; b) unstablesectionyears <strong>of</strong> observation – the scatter in the data is probablyabout equal to the precision <strong>of</strong> the observations. All threeplates at the unstable section show cumulativemovements, about 0.07m at the shoulder and mid-slope,and 0.03m at the toe.‘Frost heave’ <strong>of</strong> the road <strong>embankment</strong> is associatedwith the formation <strong>of</strong> ice lenses in seasonally frozenground. Heave results when the water freezes, attractsadditional water by capillary action, and forms ice lenses.Lenses form in all soil types by the addition <strong>of</strong> waterduring stationary or slow movement <strong>of</strong> the freezing frontinto the soil but are most common in silts and fine sand.The supply <strong>of</strong> water and ease <strong>of</strong> water movement(hydraulic conductivity) determines the extent andthickness <strong>of</strong> ice lenses. Frost heave occurs at the frostline, with T ≤ 0°C (Andersland and Ladanyi, 2004).The seasonal heaves seen in Figure 4 for theunstable section are believed to be due to frost heave.DateFigure 4. Vertical movements (settlements) at shoulder;mid-slope; and toe <strong>of</strong> the <strong>embankment</strong>3.2 Lateral Displacements from Shallow ExtensometersVibrating wire extensometers with a gauge-length <strong>of</strong> 1.0mwere installed at the toes <strong>of</strong> both test sections at a depth<strong>of</strong> 0.8m. The instruments were intended to monitor lateraldeformations at shallow depths and hopefully to relatemovements at the toe to lateral spreading and longitudinalcracking <strong>of</strong> the road surface. Unfortunately, theextensometer at the stable section failed shortly afterinstallation. Figure 6 shows horizontal strains at the toe <strong>of</strong>the unstable section plotted against time over a 28 monthperiod in 2008-2011.

28-Mar-0906-Jul-0914-Oct-0922-Jan-1002-May-1010-Aug-1018-Nov-1026-Feb-11Depth (m)Horizontal (m)28-Mar-0906-Jul-0914-Oct-0922-Jan-1002-May-1010-Aug-1018-Nov-1026-Feb-11Horizontal (m)Extensometer Horizontal Strain (%)01-Nov-0809-Feb-0920-May-0928-Aug-0906-Dec-0916-Mar-1024-Jun-1002-Oct-1010-Jan-1106-Jul-0914-Oct-0922-Jan-1002-May-1010-Aug-1018-Nov-1026-Feb-11Depth (m)Horizontal (m)0.100.050.00-0.05-0.100.100.05StableUnstableSurfaceSettlement14.4StableUnstableDown Slopea)Date Down Slopeinclinometer moved Unstable back Section towards at the Toe (Corrected) the centre <strong>of</strong> the0.80.70.60.50.40.30.20.10.01 4.40Extensometer4200.00-0.05-0.1014.4SurfaceSettlementb)Figure 6. Extensometer horizontal strain vs. time at 0.8mdepth at the toe <strong>of</strong> the unstable section0.100.050.00StableUnstableDown Date Slope<strong>embankment</strong>. This is believed to be due to creation <strong>of</strong> iceat the frost front during the freezing season and rearwardsbending <strong>of</strong> the slope indicator casing.SI at Unstable Section0-0.0514.4SurfaceSettlementc)2-0.104DateFigure 5. Horizontal movements in down-slope direction atshoulder; mid-slope; and toe <strong>of</strong> the roadThe results in Figure 6 show ongoing outwarddisplacements, currently with about 0.75% horizontalstrains at the toe <strong>of</strong> the unstable section over a period <strong>of</strong>28 months. The figure indicates fairly rapid deformationrates during the first freezing season (November 2008 toJune 2009). This may be due to natural re-densification <strong>of</strong>soil around the extensometer following installation. Afterthe first year, from July 2009 to present, the rate <strong>of</strong>horizontal straining decreased.3.3 Lateral Displacements from Slope Inclinometers atDepthSlope inclinometers were installed beneath the toes <strong>of</strong> the<strong>embankment</strong>s at both sections. The lateral movementsbeneath the toe <strong>of</strong> the stable section are small and will notbe discussed here. Figure 7 shows cumulativedisplacements measured by the slope inclinometer at thetoe <strong>of</strong> the unstable section. The figure shows that theinclinometer experienced lateral displacements away fromthe centre <strong>of</strong> the <strong>embankment</strong> at depths greater thanabout 3m. Maximum displacement <strong>of</strong> about 0.09m occursat a depth <strong>of</strong> 8m. At shallower depths, the slope68101214161819-Jun-0927-Jul-0930-Sep-0921-Jan-1015-Mar-1015-Jun-1016-Aug-1004-Oct-1016-Nov-1026-Jan-11-0.04 -0.03 -0.02 -0.01 0 0.01Cumulative Displacement (m)Figure 7. Slope Inclinometer at the toe <strong>of</strong> the unstablesectionIn general, the combined surface and deepmeasurements <strong>of</strong> displacements show that the cumulativemovements <strong>of</strong> the <strong>embankment</strong> are largely downward atthe shoulder and smaller at the toe. The resulting shearstrains push the lower levels <strong>of</strong> clay horizontally awayfrom the centre <strong>of</strong> the <strong>embankment</strong> at greater depths.

01-Nov-0809-Feb-0920-May-0928-Aug-0906-Dec-0916-Mar-1024-Jun-1002-Oct-1010-Jan-11Total Head (m)Depth (m)01-Nov-0809-Feb-0920-May-0928-Aug-0906-Dec-0916-Mar-1024-Jun-1002-Oct-1010-Jan-11Total Head (m)Depth (m)3.4 Ground Water DataFigures 8a and 8b show total heads plotted against time(indicated here as dates) at two different depths in thestable and unstable sections respectively. (Rememberthat the silty clay is much thicker beneath the unstablesection [Figure 2].) The figures imply seasonal changes inthe gradients <strong>of</strong> total head at both sections. Ground waterconditions appear to be broadly hydrostatic duringsummer months, with the ground water levelapproximately at the ground surface. During freezing,upwards gradients develop. These are believed to becaused by upward flow <strong>of</strong> water towards suction pressures(negative potentials) at the freezing front as it movesdownwards during the winter.Stable Section at the Toe1.51Depth (m)a)3.40.51.50-0.5-1-1.5-21.510.50-0.5-1-1.5-2Unstable Section at the ToeDepth (m)8.74.5b)3.5 Ground TemperaturesFigures 9 and 10 show minimum, average, and maximumtemperature pr<strong>of</strong>iles with depth for the unstable and stablesections respectively, for years 2008-09 and 2009-10.Please note the different scales used for depths in thesefigures. They arise from the different thicknesses <strong>of</strong> thefoundation soils under the two sections, (Figure 2). Again,the original ground level is at depth ‘0’.Unstable Section, Mid SlopeTemperature (˚C)-6 -4 -2 0 2 4 6 8 10 12 14 16 18 20-10123456789101145678910MinAveMax2008-092009-10Unstable Section, ToeTemperature (˚C)-6 -4 -2 0 2 4 6 8 10 12 14 16 18 200123MinAveMaxb)a)2008-092009-10Figure 8. Total head vs. time at different depths at the toe<strong>of</strong> the a) stable section; b) unstable sectionThe effects <strong>of</strong> frost action involve a combination <strong>of</strong>frost heave during a downward advance <strong>of</strong> the freezingfront, with the accompanying formation <strong>of</strong> ice lenses; anda subsequent reduction <strong>of</strong> shear strengths and highercompressibilities when the ice melts during the springthaw (Andersland and Ladanyi, 2004).Figure 9. Annual temperature envelopes betweenNovember 2008 and October 2010 for the unstablesection at the a) mid-slope; b) toeThe figures show temperatures measured by thethermistor clusters at the toes and mid-slopes <strong>of</strong> bothsections. ‘Geothermal gradient’ is the rate <strong>of</strong> change <strong>of</strong>temperature with depth in the ground. When averagetemperatures are examined in this way, the slope <strong>of</strong> theaverage temperature pr<strong>of</strong>ile can be taken as anapproximate indicator <strong>of</strong> net heat flow into, or out from, theground surface over a period <strong>of</strong> one year.

Depth (m)Depth (m)Depth (m)Depth (m)Stable Section, Mid SlopeTemperature (˚C)-6 -4 -2 0 2 4 6 8 10 12 14 16 18 20-10Min AveMax12342008-092009-105Stable Section, ToeTemperature (˚C)-6 -4 -2 0 2 4 6 8 10 12 14 16 18 200AveMaxMin12342008-092009-10Figure 10. Annual temperature envelopes betweenNovember 2008 and October 2010 for the stablesection at the a) mid-slope; b) toeFigures 9 and 10 show average temperature pr<strong>of</strong>ilesover two years at the four instrumented locations, that isat the toes and mid-slopes <strong>of</strong> the two test sections. Nosub-zero temperatures were observed during 2008-09 and2009-10. The average temperatures at all four locationsdecrease with increasing depth. This indicates a net heatflux into the foundation soils. It also supports theobservations in an earlier section that initially frozen soilhas thawed during the lifetime <strong>of</strong> the soil - there has beengeneral warming <strong>of</strong> the <strong>embankment</strong>s and theirfoundations.Figure 11 shows the monthly temperature pr<strong>of</strong>iles forone cycle <strong>of</strong> cooling and heating between November 2009and October 2010. The two graphs in Figure 11 containdata from instrument clusters at a) mid-slope and b) toefor the unstable section. (For reasons <strong>of</strong> space andclarity, we are not including observations from 2008-2009and 2010-2011.)With increasing depths, seasonal differences intemperature become less. The depth <strong>of</strong> zero annualtemperature amplitude is the depth at which the seasonalvariations <strong>of</strong> temperatures are essentially zero(Andersland and Ladanyi, 2004). Figures 11a and 11bshow that the depth <strong>of</strong> zero annual amplitude at thea)b)unstable section is about 8 – 9m below the original ground012345678910Unstable Section, Mid Slope, Nov 09-Oct 10Temperature (˚C)-6 -4 -2 0 2 4 6 8 10 12 14 16 18 20-10a)123402-Nov-09 15-Nov-09505-Dec-09 21-Jan-10619-Feb-10 15-Mar-10714-Apr-10 15-May-10815-Jun-10 16-Jul-10916-Aug-10 13-Sep-101025-Sep-10 04-Oct-1011Unstable Section, Toe, Nov 09-Oct 10Temperature (˚C)-6 -4 -2 0 2 4 6 8 10 12 14 16 18 2002-Nov-0905-Dec-0919-Feb-1014-Apr-1015-Jun-1016-Aug-1025-Sep-1015-Nov-0921-Jan-1015-Mar-1015-May-1016-Jul-1013-Sep-1004-Oct-10Figure 11. Monthly temperature pr<strong>of</strong>iles betweenNovember 2009 and October 2010 for the unstablesection at the a) mid-slope; b) toelevel.The respective temperatures pr<strong>of</strong>iles for the mid-slopeand toe converge at about the same depth, although thereis approximately a 1.6°C difference between the twovalues. The soil underneath the <strong>embankment</strong> is colderthan soil at the same depth underneath the toe. It isbelieved that this can be explained by the previouspresence and thawing <strong>of</strong> a frost bulb underneath the<strong>embankment</strong> or alternatively by differences in thermalconductivity between gravel in the <strong>embankment</strong> and clayin the foundation soils. This observation could have beenverified if thermistor strings had been installed under thecentre <strong>of</strong> the <strong>embankment</strong>. Perhaps unfortunately, safety,snow clearing, and grading made this impossible. Coolertemperatures beneath the <strong>embankment</strong> may also be dueto an insulating cover <strong>of</strong> snow beneath the toe, combinedwith the effects <strong>of</strong> show clearing on the roadway.4 SUMMARYb)

The paper reports and analyzes measurements <strong>of</strong> surfacesettlements, toe displacements, pore water pressures andtemperatures from a low <strong>highway</strong> <strong>embankment</strong> nearThompson in northern Manitoba.The deformation results indicate a combination <strong>of</strong>seasonal and cumulative displacements, with largerdisplacements at the toe than at the shoulder. The resultsshow a combination <strong>of</strong> seasonal heaving and lateralspreading. The pore water pressure results suggest thedevelopment <strong>of</strong> cyclic seasonal gradients <strong>of</strong> total head.These indicate hydrostatic water pressure conditionsduring summer months and upwards flow during thefreezing season. Measured temperatures also showedseasonal changes. Net heat flow into the ground ispossibly a confirmation <strong>of</strong> general warming in the area,although it we note that only two years <strong>of</strong> readings havebeen collected. The data confirm field observations <strong>of</strong> thethawing <strong>of</strong> ice that was present in the first drilling <strong>of</strong> thesite in 1991 but absent in recent drilling in 2008.ACKNOWLEDGEMENTSFinancial support was provided by the Natural Sciencesand Engineering Research Council <strong>of</strong> Canada (NSERC)and by Manitoba Infrastructure and Transportation (MIT).Technical and logistical support was provided by KerryLynch at the University <strong>of</strong> Manitoba, by engineers andtechnologists <strong>of</strong> Manitoba Infrastructure andTransportation in Winnipeg and Thompson, and by KellyBindle at Bindle Engineering in Thompson MB.REFERENCESAndersland, O.B. and Ladanyi, B., (2004). Frozen GroundEngineering (2nd Edition). John Wiley & Sons.Batenipour, H., Kurz, D., Alfaro, M., and Graham, J.2009a. Effect <strong>of</strong> Temperature on the 1-D Behaviour<strong>of</strong> Plastic Clay. In Proceedings <strong>of</strong> 62 nd CanadianGeotechnical Conference, Halifax NS, September2009, pp. 47-52.Batenipour, H., Kurz, D.R., Alfaro, M.C., Graham, J. andNg, T.N.S., 2009b. Highway Embankment onDegrading Permafrost. In proceedings <strong>of</strong> the 14thConference on Cold Regions Engineering in Duluth,Minnesota, USA, pp. 512-521.Batenipour, H., Kurz, D.R., Alfaro, M.C., Graham, J. andKalynuk, K., 2010. Results from an InstrumentedHighway Embankment on Degraded Permafrost. Inproceedings <strong>of</strong> the 63 rd Canadian GeotechnicalConference & 6 th Canadian Permafrost Conference.Calgary: 512-519.Brown, R.J.E. 1967. Permafrost in Canada. Canada,Geological Survey Map 124A, first edition.CCCSN (Canadian Climate Change Scenarios Network)2009. Arctic Ensemble Scenarios.Hinkel, K.M., Nelson F.E., Park W., Romanovsky V.,Smith O., Tucker W., Vinson T. and Brigham L.W.,2003. Climate Change, Permafrost, and Impacts onCivil Infrastructure, United States Arctic ResearchCommission: Permafrost Task Force Report, SpecialReport 01-03.IPCC (Intergovernmental Panel on Climate Change)2007. Summary for policymakers. In: Climate change2007: The physical science basis. Contribution <strong>of</strong>Working Group I to the Fourth Assessment Report <strong>of</strong>the Intergovernmental Panel on Climate Change. S.Solomon; D. Qin; M. Manning; Z. Chen; M. Marquis;K.B. Averyt; M.Tignor; H.L. Miller (eds.). Cambridge,UK, and New York, NY: Cambridge University Press.Konrad, J.-M. 2008. Freezing-induced water migration incompacted base-course materials. CanadianGeotechnical Journal 45, 895-909.Koyama, M. and Sasaki, H,, 1967. Frost Heave <strong>of</strong> Roadsin Hokkaido and Its Countermeasures, Physics <strong>of</strong>Snow and Ice : proceedings, 1(2): 1323-1331Nelson, F.E. and Outcalt, S.I.: 1982, Anthropogenicgeomorphology in northern Alaska, PhysicalGeography 3, 17–48.Osterkamp, T.E. and Lachenbruch, A.H. 1990. Thermalregime <strong>of</strong> permafrost in Alaska and predicted globalwarming. ASCE Journal <strong>of</strong> Cold Regions Engineering4, 38-42.Williams, P. J. 1986, Pipelines & Permafrost: Science in aCold Climate, Carleton University Press, Don Mills,Ontario, 129 pp.