Christopher Byrum, Ph.D., P.E. Geotechnical Engineering/Research

1. Help You Think Like Bridge Geotechnical Engineer.

2. Help You Better Understand Foundations.

3. Build Appreciation for the Bridge Approach Embankments.

4. Discuss Cofferdam Design and Construction.

5. Some Foundation/Embankment Case Studies.

6. Better understand Load and Resistance Factor Design (LRFD)

8:00 Geotechnical Engineering and Michigan Geology Christopher R. Byrum, PhD, PE (SME) 8:45 MDOT Perspectives on Geotechnical Engineering for Bridges Ryan W. Snook, PE and/or Richard B. Endres, PE (MDOT) 9:30 Cofferdam Design and Construction Basics: Anthony Pietrangelo, PE (MDOT) 10:00 Break (15 minutes) 10:15 Bridge Abutment Analysis and Design Example: Evaluation through Construction Christopher R. Byrum, PhD, PE (SME) and Douglas Parmerlee, PE (AECOM)

1:00 Increased LRFD Axial Resistance Factors for Piling Using Static Load Test and PDA Christopher G. Naida, PE (SME) and Christopher Johnecheck, PE (MDOT) 1:35 Bridge Replacements on I‐196: Teamwork between the Bridge and Geotechnical Engineers Jonathan Zaremski, PE et al (SOMAT) 2:15 Rock Engineering ‐ I‐196 WB Bridge over the Grand River, Grand Rapids MI Melinda L. Bacon, PE (SME) 3:00 Break (15 minutes)

3:00 Break (15 minutes) 3:15 Wadhams Road Bridge Replacement: Bridging Over a Moving Site Douglas Parmerlee, PE, et al (AECOM) 4:00 Geosynthetics and Lightweight Fills for Bridge Abutments and Approaches Christopher R. Byrum, PhD, PE (SME) 4:45 FHWA’s GEOTECHTOOLS software and closing remarks Christopher R. Byrum, PhD, PE (SME)

MICHIGAN’S GEOLOGY

REFERENCE: “Geology of Michigan” Dorr & Eschman. University of Michigan Press

Mantle

Core

Inner Core

1800 Miles

3160 Miles

3975 Miles

Pre-Cambrian Mountains2.5 to 3 billion Years Ago

Unconformity

2.5 Billion+(brown) 0.6 Billion-

(tan)

2.9 Billion+(green)

1.65 Billion+/-

1.2 Billion+/-

0.6 Billion-

410 million

280 million

Jurassic Seds.140 million

The Michigan Basin

DEPOCENTER = Bottom of down-warpedbowl-like layers DOW CHEMICAL

Optimum location to mine various BRINES

About 15,000 years ago

About 15,000 years agoC. Byrum

State Fossil: Mastadon

Mastadon Finds

About 8,000 years agoRetreat Rate ≈ 500’/yr

HURON RIVER

HURON RIVER

HURON RIVER

Artesian Zone

From MDOT’s “Field Manual of Soils Engineering”

Fort Wayne

Initial Glacial Lakebed Clay Deposition

From Dorr & Eschman “Geology of Michigan”

Fort WayneDefiance

Glacial Re-Advance, Over-Consolidates initial Lakebed Clay New Lakebed Clay Deposition

Upper Clays SPT = 10-30 bpfLower Clays SPT = 50-100+ bpf

From Dorr & Eschman “Geology of Michigan”

MechanismsFor

Preconsolidationof

Lakebed Clays

Highly Overconsolidated Till and Rock

SPT > 80-100 bpf

Continental Glacier Lobe

STAGE 1 – Full Ice Lobe Weight during the Deep Freeze

G.W.T.

STAGE 2 –Melting, Ice Lobe Floats, Soft Clay Deposition

Soft Clay

Floating Ice Mass

G.W.T.

STAGE 3 – Re-Freeze and Water Table Lowering

Extreme Preconsolidation NoneG.W.T.

Soft Clay

Floating Ice Mass

STAGE 4 – Melting, Ice Lobe Floats, Soft Clay DepositionG.W.T.

Soft Clay

STAGE 5 – Re-Freeze and Water Table Lowering

G.W.T.Extreme Preconsolidation None

Soft Clay

STAGE 6 – Continued Melting/Lowering, Occasional Contact

G.W.T.

STAGE 7 – Glacial Lake Stanley!! Sun-Baking and Lowering

G.W.T.

Very Soft Clay

STAGE 8 –Water Rising After Final Melting, Very Fine/Soft Clays

G.W.T.

Soft Clay Baked Crus

STAGE 9 –Water Table Lowering and Sun Baking

G.W.T.

Peat Marshes

From MDOT’s “Field Manual of Soils Engineering”

Melt-water Clay/Silt Liner

From MDOT’s “Field Manual of Soils Engineering”

From MDOT’s “Field Manual of Soils Engineering”

Soft Clay/Marl

Sedimentary-Amorphous Peat

Fibrous Peat

Woody Peat

MDOT: Leader in Soft Soil Engineering, see 1920’s TRB proceedingsregarding MDOT swamp embankment research = great work!

Massive Method-B Treatment of Peat Marsh

No Swamp – Like New

Continuously Breaking Up and Moving over Swamp

Exposed Piers Due to Bed Degradation

Pier Failure, California

RIVER SCOURNormal Flow

Flood Events500 yr. Surface

100 yr. Surface

500 yr. Channel

100 yr. Channel

Water Goes Up-Channel Goes DownWater Goes Down-Channel Fills InHigher Flow Velocity-Bigger Particles Suspended

CONTRACTION SCOUR

Normal Water Surface

Flood Events500 yr. Surface

100 yr. Surface

LOCAL SCOUR

SCOUR WITH A PIER

The pier is an obstruction to flow. The eddie currents around the pier (small tornado-like features) chew up the channel bottom locally around the pier

Design Factors:1. Local Scour Depth2. Ship Impact3. Debris Impact4. Ice Impact/Flow5. Vertical/Lateral Loads6. Wind/Earthquake Loading7. Combinations of above

DESIGN FOR SCOUR

Check:1. Stiff enough laterally?2. How deep below scour?3. How to get that deep?4. Abutment Stability

MV

Pv Pl (pin connection)

Soil

Piles

Abutment Failure in Iowa

LRFD- Basic Concepts

# of

Eng

inee

rs

0 1 2Predicted/Actual Load Magnitude

0 1 2Predicted/Actual Soil Resistance

Structures ResearchGeotechnical Research

# of

Eng

inee

rs

0 1 2Predicted/Actual (Normalized) Values

LRFD Research

Plot shows:Load Factor = 1Resistance Factor = 1

Mix random Geo-Engineer with random Structural Engineer and Failure Probability isrelatively high here.

# of

Eng

inee

rs

0 1 2Factored Normalized Resistances

Old School FS = 2 Concept

Plot shows:Load Factor = 1Resistance Factor = 0.5

Probability of Failure isrelated to area of small yellow zone

# of

Eng

inee

rs

0 1 2Factored Normalized Resistances

LRFD Research

Plot shows:Load Factor = 1/0.6 = 1.67 Resistance Factor = 1/1.3 = 0.77

Approx. FS = 1.67/0.77 = 2.17

Probability of Failure isrelated to area of small yellow zone

# of

Eng

inee

rs

0 1 2Factored Normalized Resistances

Geotechnical ResearchBest Procedure = 1/1.35 0.75Overestimation biased = 1/1.45 0.7Underestimation biased = 1/1.55 0.65