2-bcrra2013 ws frost-ulring alaskan design
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Joel D. Ulring, P.E.Golder Associated Inc.
Anchorage, Alaska USAJune 24, 2013
BCRRA ConferenceTrondheim, Norway
June 25-27, 2013
WORK SHOP 1 - PAVEMENT DESIGN IN COLD REGIONS
ORDER OF PRESENTATION
Introduction
Anchorage Facts
Municipality of Anchorage Pavement Design
Practice
State of Alaska Pavement Design Practice
Summary
July 2, 2013 2
INTRODUCTION
July 2, 2013 3
Joel D. Ulring P.E.Senior Geotechnical Engineer
Golder Associates Inc.Anchorage Alaska
18 Years Public Service in Minnesota Counties
10 Years as Geotechnical Engineer Consultant
ANCHORAGE FACTS
July 2, 2013 4
AnchorageArea Map Population
- Alaska 790,000 - Anchorage 300,000
Significant Growth in 1970’s
ANCHORAGE FACTS
July 2, 2013 5
ANCHORAGE FACTS
Anchorage Facts 61° North Latitude Design Thawing Index
Air = 4000 °DaysSurface = 3200 °Days
Design Freezing IndexAir = 3200 °DaysSurface = 6800 °Days
Typical Frost PenetrationDepth 9 feet (2.75 m)
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ANCHORAGE PAVEMENT DESIGN
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Municipality of
Anchorage Pavement
Design
ANCHORAGE PAVEMENT DESIGN
MOA Design Criteria Manual – Chapter 1 Streets Section 1.10 Road Structural Fill Design
Primary Design Objectives
Reduce freezing and thawing impacts on road
Obtain roadway/Pavement design life
July 2, 2013 8
ANCHORAGE PAVEMENT DESIGN
MOA Design Criteria Manual – Chapter 1 Streets Section 1.10 Road Structural Fill Design
Mandatory Design Objectives
Mitigate the formation of ice lenses
Prevent pumping of subgrade
Prevent differential frost heave
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ANCHORGAE PAVEMENT DESIGN
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Differential FrostHeaving of InsulatedPavement Section
ANCHORAGE PAVEMENT DESIGN
PAVEMENT DESIGN PROCESS Subsurface Soil Investigation (1 borehole ≈ 300 ft.)
Laboratory Testing of Collected Soil Samples
Soil Frost Group Index DeterminedFrost Group: NFS, F1, F2, F3, F4
Thermal Analysis (Berg2)
Design Pavement Section
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ANCHORAGE PAVEMENT DESIGN
July 2, 2013 12
MOA Frost GroupSoil Classification
ANCHORAGE PAVEMENT DESIGN
Typical Soil Typesof
Anchorage
July 2, 2013 13
ANCHORAGE PAVEMENT DESIGN
MOA Design Criteria Manual – Chapter 1 Streets Section 1.10 Road Structural Design Methods
Minimum Section Complete Protection Method
Excavate and replace frost susceptible soils with non frost susceptible soil (NFS)
Limited Subgrade Frost Penetration Method Allows frost penetration of 10% into subgrade based on
thickness of structural section
Provision for use of rigid board insulation to reduce structural section thickness.
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ANCHORAGE PAVEMENT DESIGN
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Minimum Structural SectionNFS Soil Subgrade
2” AC
2” Leveling Course
6” Type II-a Fill
12” Type II Fill
Subgrade(F1 Soils)
ANCHORAGE PAVEMENT DESIGN
Complete Protection MethodTypical Pavement Structural Section
2” AC
2” Leveling Course
18” Type II-a Fill
2” Board Insulation
Type II Fill 24”- 30”
Calculated Frost DepthSubgrade(F2, F3 or F4 Soils)
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ANCHORAGE PAVEMENT DESIGN
Limited Subgrade Frost Penetration MethodTypical Pavement Structural Section
2” AC
2” Leveling Course
18” Type II-a Fill
2” Board Insulation
Type II Fill 18”- 26”
10% Frost Penetration
Calculated Frost DepthSubgrade(F2, F3 or F4 Soils)
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ANCHORAGE PAVEMENT DESIGN
TYPICAL STREET DESIGN SECTIONLimited Subgrade Frost Penetration Method
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ANCHORAGE PAVEMENT DESIGN
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LEVELING COURSE GRADATION
ANCHORAGE PAVEMENT DESIGN
Type IIU.S. Std. SieveCumulative %
Passing by Weight8“ 1003“ 70-100
1-1/2“ 55-1003/4“ 45-85#4 20-60
#10 12-50#40 4-30#200 2-6
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Type II-aU.S. Std. SieveCumulative %
Passing by Weight3“ 1003/4“ 50-100#4 25-60#10 15-50#40 4-30#200 2-6
CLASSIFIED FILL GRADATIONS
ANCHORAGE PAVEMENT DESIGN
COMMENTS How should current climate trends be accounted for in
design?
Should design parameters (Freezing & Thawing Indices) within Berg2 analysis be adjusted?
Should another thermal analysis model be considered?
MOA is currently reviewing their pavement design manual.
July 2, 2013 21
THANK YOU !QUESTIONS ?
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