02 - dealing with permafrost degradation under airport … 13 sept/02... · 2018-09-18 ·...

DEALING WITH PERMAFROST DEGRADATION UNDER AIRPORT

PAVEMENTS

Ludomir Uzarowski, Rabiah Rizvi, Mark Musial, Golder Associates Ltd.Susan Tighe, University of Waterloo

SWIFT, CAPTGNiagara Falls, September 13, 2018

PRESENTATION OUTLINE

September 18, 2018 2

Introduction Permafrost Impact of permafrost degradation Geotechnical investigation Possible treatments Case studies Summary

INTRODUCTION

INTRODUCTIONTypical challenges for airport pavement design and construction in the North

Severe climatic conditions Severe winters

Deep frost penetration Permafrost and frost heaving

Soil and water conditions Typically glacial till Undulating bedrock Shallow water

Difficult construction conditions Short construction season Long distances Poor roads

INTRODUCTIONTypical challenges for airport pavement design and construction in the North

Remote locations and low human population

High construction cost Few contractors available Design

New challenges Custom specifications required

Limited experience and technology? Lack of quality materials QC/QA

Difficult and expensive

Frost susceptibility – soil characteristics that promote ice segregation and heaving when soil freezes

Typically differential in nature In general, fine-grained soils are frost

susceptible and coarse-grained soils are not Heaving occurs not only from when water in

soil turns to ice and forms ice lenses, but also in fine grained soils having high capillarity, silts and fine grained sands, ice lenses form due to water migration

PERMAFROST

Permafrost – perennially frozen soil

Active layer – in an area of permafrost, the top layer of ground subject to annual freezing and thawing

PERMAFROST

TE Osterkamp, University of Alaska CR Burn, Carleton University

PERMAFROST

Glen Argue “Canadian Airfield Pavement Engineering Reference”

PERMAFROST

Glen Argue “Canadian Airfield Pavement Engineering Reference”

PERMAFROST

Glen Argue “Canadian Airfield Pavement Engineering Reference”

FAA

PERMAFROST

Glen Argue “Canadian Airfield Pavement Engineering Reference”

PERMAFROST

PERMAFROST DEGRADATION

Permafrost degradation is also more drastic due to climate change

Alaska DOT

PERMAFROST DEGRADATION

PERMAFROST DEGRADATION

Nature of ground coverDescription of observed pavement

failuresSettlements, cracking, frost heaving

Subsurface investigationDrilling or test pitsSubsurface temperature monitoringPresent thickness of active layerDescription of frozen material

Drainage conditions

PERMAFROST INVESTIGATION

Glen Argue “Canadian Airfield Pavement Engineering Reference”

PERMAFROST INVESTIGATION

ThermistorsPrecision temperature

sensing devices at various depthProbe tip includes a semi

conductorTemperature change

cause change in electrical resistance

PERMAFROST INVESTIGATION

PERMAFROST INVESTIGATION

FROST HEAVING

Pavement treatment to address permafrost degradationEmergency repairsPavement structural

rehabilitation

PERMAFROST DEGRADATION TREATMENT

Structural repairs Provide complete frost protection – install

non-frost susceptible materials (max 1.8 m)Accept reduced subgrade strength during

seasonal permafrost thaw – differential frost having to be anticipated

InsulationRelocation of airside facilities

PERMAFROST DEGRADATION TREATMENT

Pavement designs if relocation not feasibleFull depth reconstruction to a

depth of frost penetrationSoil stabilizationGeogrid structureSingle layer with underlying

geotextilePillow structure

PERMAFROST DEGRADATION TREATMENT

CASE 1

CASE 1

CASE 1

CASE 1

CASE 1

CASE 1

Airfield Pavement Roughness Guidelines (TC)

CASE 1

Pavement condition Keel and non-keel zone

Settlements, frost heaves, low to high severity cracking, low severity ravelling

Poor (bumpy) ride particularly on two sections in the keel zone

Permafrost Melted or melting

Drainage Very poor condition of surface drainage No subsurface drainage

Emergency repairs and drainage improvement Pavement rehabilitation recommended in near future

CASE 1

CASE 2

CASE 2

CASE 2

Pavement condition Low to high severity cracking, frost heaving,

settlements – severe in non-keel zones, fair ride quality in the keel zone

Permafrost Melted or melting

Drainage Poor surface drainage Failed subsurface drainage system

Emergency repairs and drainage improvement Pavement rehabilitation recommended in near future

CASE 2

Continuous, very severe apron pavement settlements and cracking

CASE 3

Tilting of buildings and foundations

CASE 3

Capacitively-coupled electrical resistivity imaging (C-CERI)

OhmMapper using C-CERI system in addition to regular investigation

Electrical resistivity of the surface – laterally and vertically

High ice content or permafrost increase resistivity (warm colors)

Lower resistivity (cool colors) –higher water content

CASE 3

OhmMapper using C-CERI system

CASE 3

Relocation of ATB, apron and access road to a new area with no permafrost

CASE 3

Large part of Canada is in the discontinuous and scattered permafrost zone

Permafrost degradations poses serious problems for airports due to differential settlements and cracking

Differential frost heaving is also typically observed in these areas

SUMMARY

Geotechnical investigation and condition monitoring are necessary

Pavement treatment to address permafrost degradation Emergency repairs Pavement structural

rehabilitationDrainage improvements

SUMMARY

THANK YOU !

QUESTIONS ?

luzarowski@golder.com