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
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