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ASCE Fall Technical SeminarASCE Fall Technical Seminar
Standard of Practice for Levee DesignStandard of Practice for Levee Design
Chris GrovesChris GrovesOctober 2009October 2009
Before Katrina one could Before Katrina one could describe levees as the describe levees as the
stepchild of the engineeringstepchild of the engineeringstepchild of the engineering stepchild of the engineering professionprofession
After Katrina our attitude about the After Katrina our attitude about the risk posed by the levee system was risk posed by the levee system was
differentdifferent
2
Even the Midwest floods of 1993 did Even the Midwest floods of 1993 did not cause us to rethink the risks. not cause us to rethink the risks.
After all, outside a few problems with After all, outside a few problems with federal levees, the levee system federal levees, the levee system
performed quite well. Overtopping of performed quite well. Overtopping of the agricultural levees had been the agricultural levees had been gg
expected and as a matter of policy expected and as a matter of policy this overtopping help protect the this overtopping help protect the
urban levees.urban levees.
Katrina managed to change our Katrina managed to change our understanding of acceptable levee understanding of acceptable levee
performance overnight. The lessons performance overnight. The lessons learned in the 1927 Mississippi River learned in the 1927 Mississippi River flood had long since been forgottenflood had long since been forgotten
Flooding criteria has led to most of Flooding criteria has led to most of the problems we have experiencedthe problems we have experienced
•• A 100A 100--year or greater flood has a 26% probability of year or greater flood has a 26% probability of occurrence in the life of a 30occurrence in the life of a 30--year mortgage. People are year mortgage. People are dropping the flood insurance when they have only 100dropping the flood insurance when they have only 100--year protection.year protection.
•• Banks require fire and storm insurance for much less likely Banks require fire and storm insurance for much less likely events. Banks should require flood insurance until a much events. Banks should require flood insurance until a much higher level of protection is provided.higher level of protection is provided.
•• From a public safety prospective, society should keep the From a public safety prospective, society should keep the general public out of the flood plain until a much higher general public out of the flood plain until a much higher level of protection is provided.level of protection is provided.
3
How is flood frequency currently How is flood frequency currently being defined? The term “free board” being defined? The term “free board” is being replaced. Now it is the 90 or is being replaced. Now it is the 90 or
95 percent probability of 95 percent probability of nonexceedance.nonexceedance.
EM 1110EM 1110--22--1913 has become the 1913 has become the manual for levee design. Other manual for levee design. Other
documents are referenceddocuments are referenced
On the first page the document states On the first page the document states “Even though levees are similar to “Even though levees are similar to small earth dams they differ from small earth dams they differ from
earth dams in the following important earth dams in the following important respects:respects:
a)a) A levee embankment may become A levee embankment may become saturated for only a short period of timesaturated for only a short period of timesaturated for only a short period of time saturated for only a short period of time beyond the beyond the limit of capillary saturationlimit of capillary saturation,,
b)b) Levee alignment is dictated primarily by Levee alignment is dictated primarily by flood protection requirement, which often flood protection requirement, which often results in construction on poor foundation, results in construction on poor foundation, and….and….
4
Modes of failure are identified as,Modes of failure are identified as,
•• OvertoppingOvertopping
•• Surface erosionSurface erosion
•• Internal erosion (piping)Internal erosion (piping)
•• Slides within the levee Slides within the levee embankment or the foundation embankment or the foundation soil.soil.
The differences in urban levees and The differences in urban levees and agricultural levees.agricultural levees.
•• Agricultural levees are generally constructed to Agricultural levees are generally constructed to provide a crest elevation above the 50provide a crest elevation above the 50--to100to100--yr level yr level of protection.of protection.
•• Agricultural levees were generally not designed by a Agricultural levees were generally not designed by a geotechnical engineer.geotechnical engineer.g gg g
•• Agricultural levees have seen poor construction and Agricultural levees have seen poor construction and repair practices.repair practices.
•• Urban levees have been constructed over the top of Urban levees have been constructed over the top of agricultural levees.agricultural levees.
•• Urban levees have had some borings and Urban levees have had some borings and geotechnical input.geotechnical input.
•• Urban levees protect lives.Urban levees protect lives.
Manual describes a phased Manual describes a phased investigation includinginvestigation including
Preliminary geological investigation Preliminary geological investigation including an office study based on available including an office study based on available information and a field survey to define the information and a field survey to define the topography, evidence of past problems, and topography, evidence of past problems, and natural and manmade features.natural and manmade features.
Subsurface explorations with two phases of Subsurface explorations with two phases of borings, test pits, geophysics, pump test, borings, test pits, geophysics, pump test, etc.etc.
5
While aerial photographs are While aerial photographs are mentioned a geomorphologic study is mentioned a geomorphologic study is
not specifically describednot specifically described
Seepage and stability analysis are Seepage and stability analysis are described as the same scope one described as the same scope one
would do for a dam.would do for a dam.
•• Case I Case I –– End of ConstructionEnd of Construction
•• Case II Case II –– Sudden drawdownSudden drawdown
•• Case III Case III –– Steady Seepage from full flood stageSteady Seepage from full flood stage
C IVC IV E th k ( ll t i d)E th k ( ll t i d)•• Case IV Case IV –– Earthquake (normally not required)Earthquake (normally not required)
Steady Seepage becomes a problem for Steady Seepage becomes a problem for most unzoned homogenous most unzoned homogenous
embankments. When the phreatic embankments. When the phreatic surface breaks out on the face of the surface breaks out on the face of the
embankment the factor of safety drops. embankment the factor of safety drops. This issue is often addressed with one This issue is often addressed with one
f ff for more of the following.or more of the following.
•• A small cohesion of say 100 psf for clayA small cohesion of say 100 psf for clay
•• Ignoring shallow circles that do not reach the crest. Also Ignoring shallow circles that do not reach the crest. Also addressed in section 6addressed in section 6--8 of EM 1913.8 of EM 1913.
•• Transient seepage analysis (results subject to assumptions)Transient seepage analysis (results subject to assumptions)
•• A ruleA rule--ofof--thumb seepage geometry has been assumed.thumb seepage geometry has been assumed.
•• Seepage berms.Seepage berms.
6
Factor of safety criteria are as followsFactor of safety criteria are as follows
•• 1.4 for steady seepage.1.4 for steady seepage.
•• 1.3 for end of construction 1.3 for end of construction
•• 1.0 to 1.2 for rapid drawdown1.0 to 1.2 for rapid drawdown
•• A series of exceptions are also A series of exceptions are also stated.stated.
Guidance for design of levees Guidance for design of levees generally follows guidance generally follows guidance
for earth dam.for earth dam.Then why does it appear that Then why does it appear that levees perform poorly in levees perform poorly in
comparison?comparison?
What are the principal hazards for What are the principal hazards for levees (failure modes)?levees (failure modes)?
•• OvertoppingOvertopping
•• UnderseepageUnderseepage
•• Slope StabilitySlope Stability
•• Through Seepage and Through Seepage and PenetrationPenetration
•• Animal BurrowsAnimal Burrows
7
Overtopping Overtopping –– could be a low spot or could be a low spot or flood could exceed the designflood could exceed the design
Under seepage Under seepage –– starts as a small starts as a small boil and deteriorates with each floodboil and deteriorates with each flood
Slope instability Slope instability –– usually the result usually the result of a seepage problemof a seepage problem
8
Through seepage Through seepage –– a construction a construction problem, a utility, or animal burrowproblem, a utility, or animal burrow
Animal BurrowAnimal Burrow
What is What is Acceptable Risk?Acceptable Risk?
•• What is risk?What is risk?
•• Who determines what is Who determines what is acceptable?acceptable?
9
Risk = (probability) X (consequences)
DefinitionDefinition
Risk is never acceptable unconditionally. Risk is only acceptable if some benefit
can compensate for the risk
RiskRisk
can compensate for the risk.Fischhoff 1981
•• A dam is constructed for the A dam is constructed for the benefit of the owner of the dambenefit of the owner of the dam–– It is not acceptable to increase the It is not acceptable to increase the
risk to people downstream whorisk to people downstream who
DamsDams
risk to people downstream who risk to people downstream who receive no benefit.receive no benefit.
–– Therefore, we use very high Therefore, we use very high standards in the design and standards in the design and construction of a dam.construction of a dam.
10
CriteriaCriteria
•• A levee is constructed for the A levee is constructed for the benefit of the people who live benefit of the people who live behind the leveebehind the levee
LeveesLevees
behind the levee.behind the levee.
•• Can they accept some risk?Can they accept some risk?
•• Engineers know that a dam Engineers know that a dam should have an impervious zone should have an impervious zone and a pervious drainage zoneand a pervious drainage zone——itit is not acceptable for seepage is not acceptable for seepage to breakout on the downstream to breakout on the downstream facefaceface.face.
•• Engineers followed the practice Engineers followed the practice of the farmers for the levees.of the farmers for the levees.
11
Typical EmbankmentUSACE Manual
•• Farmers understood the risk.Farmers understood the risk.
•• They kept an eye on the river They kept an eye on the river and were quick to evacuate farm and were quick to evacuate farm equipment and personalequipment and personal
PerceptionsPerceptions
equipment and personal equipment and personal belongings.belongings.
•• Prosperous farmers would move Prosperous farmers would move family up on bluffs and continue family up on bluffs and continue farming flood plains.farming flood plains.
•• When the general public began When the general public began moving onto the flood plain they moving onto the flood plain they did not understand the risk.did not understand the risk.
•• They were often not sure where They were often not sure where
PerceptionsPerceptions
the river was located.the river was located.
•• They did not know what levees They did not know what levees looked like, who constructed looked like, who constructed them, or who maintained them.them, or who maintained them.
12
•• The general public does not The general public does not know what a 100know what a 100--year levee is.year levee is.–– Does it mean that the flood comes Does it mean that the flood comes
about every 100 years?about every 100 years?
PerceptionsPerceptions
–– Does it mean that because there Does it mean that because there was a large flood 10 years ago was a large flood 10 years ago there will be 90 years before the there will be 90 years before the next one? “I don’t plan to live next one? “I don’t plan to live another 90 years, so I must be ok.”another 90 years, so I must be ok.”
•• “I am protected by a levee.”“I am protected by a levee.”–– Protected means there will never Protected means there will never
be a flood greater than the levee’sbe a flood greater than the levee’s
PerceptionsPerceptions
be a flood greater than the levee s be a flood greater than the levee s capability to protect.capability to protect.
•• Has this misconception of Has this misconception of terminology been cleared up by terminology been cleared up by FEMA and the USACE?FEMA and the USACE?
PerceptionsPerceptions
•• NO! But lately they have been NO! But lately they have been trying.trying.
13
Congress and FEMACongress and FEMA
•• Has defined the Base Flood as Has defined the Base Flood as the flood with a 1 percent the flood with a 1 percent chance of exceedance on an chance of exceedance on an annual basis. annual basis.
•• When a levee provides When a levee provides protection for a flood with a 1% protection for a flood with a 1% probability, people within the probability, people within the protected zone are not required protected zone are not required to purchase flood insurance.to purchase flood insurance.
•• BAD IDEA!BAD IDEA!
•• In a 30In a 30--year period there is a year period there is a 26% chance that an event with a 26% chance that an event with a 1% annual probability will occur1% annual probability will occur
RealityReality
p yp y
•• People that pass on the flood People that pass on the flood insurance for their home are insurance for their home are betting they will not lose their betting they will not lose their greatest asset for the sake of greatest asset for the sake of saving on insurance.saving on insurance.
•• Most people in the Midwest have Most people in the Midwest have storm insurance. The banks storm insurance. The banks require it with the mortgage. Is require it with the mortgage. Is one home in four destroyed by one home in four destroyed by
RealityReality
tornados?tornados?
•• Who carries much of the blame Who carries much of the blame when the levee is overtopped?when the levee is overtopped?
•• USACE took the blame for New USACE took the blame for New Orleans.Orleans.
14
From a social standpointFrom a social standpoint
•• What is wrong with the system?What is wrong with the system?
•• A 1% chance of failure each A 1% chance of failure each year is unacceptable when year is unacceptable when people understand the riskpeople understand the riskpeople understand the risk.people understand the risk.
•• Farmers want to sell the land for Farmers want to sell the land for development and retire.development and retire.
•• Developers want to develop the Developers want to develop the valuable floodplain near cities forvaluable floodplain near cities for
The path followedThe path followed
valuable floodplain near cities for valuable floodplain near cities for a profit.a profit.
•• Cities want the tax baseCities want the tax base
15
•• Congress and FEMA has set a Congress and FEMA has set a standard with too much risk.standard with too much risk.
•• Engineers are willing to use a Engineers are willing to use a level of practice that results in level of practice that results in
Compounding riskCompounding risk
pptoo many failures.too many failures.
•• Home owners do not want to Home owners do not want to purchase the insurance.purchase the insurance.
•• Who is to blame?Who is to blame?
From an Engineering StandpointFrom an Engineering Standpoint
•• What is wrong with the system?What is wrong with the system?
•• Hydrology criteriaHydrology criteria——who would who would design a bridge or building with a design a bridge or building with a 26% chance of failure in a 3026% chance of failure in a 30--
EngineeringEngineering
year design life?year design life?
•• Geotechnical explorationGeotechnical exploration——who who would design a structure with would design a structure with borings spaced at 1,000 feet borings spaced at 1,000 feet with closer spacing at identified with closer spacing at identified problemsproblems
16
•• Geotechnical analysisGeotechnical analysis——who who would design a dam without would design a dam without internal drainage features?internal drainage features?
EngineeringEngineering
•• Geotechnical stability and Geotechnical stability and underseepageunderseepage——who would who would consider observation during consider observation during loading to be an important tool to loading to be an important tool to find design deficiencies?find design deficiencies?
Finding the hidden problemFinding the hidden problem
120‐year flood
100‐year flood
Residual RiskResidual Risk
Levee
Residual Risk
17
What have we learned and what What have we learned and what should we do?should we do?
•• Go for a 500Go for a 500--year (.2% year (.2% probability) criteria and stress probability) criteria and stress that there is still a 6% probabilitythat there is still a 6% probability
LessonsLessons
that there is still a 6% probability that there is still a 6% probability of failure in a 30of failure in a 30--year period, or year period, or suggest Probable Maximum suggest Probable Maximum Storm criteria used in sizing Storm criteria used in sizing spillways for damsspillways for dams
•• Stress the education of riskStress the education of risk
•• Stress that potential for loss of Stress that potential for loss of life should be considered in life should be considered in residential zoning. When aresidential zoning. When a
LessonsLessons
residential zoning. When a residential zoning. When a warehouse or factory is flooded warehouse or factory is flooded the risk to life is much lessthe risk to life is much less
•• Go for greater levee setbacks Go for greater levee setbacks from the river banksfrom the river banks
Questions???Questions???
1
Design and Constructionof Micropiles
Fall Technical SeminarASCE Geotechnical Subcommittee – St. LouisOctober 30, 2009
John R. Wolosick, P.E.
Hayward Baker Inc.
Hayward Baker
2003
Calendar Art
Micropiles are…
High capacity (up to 500 tons design load), typically small diameter (2”-12”+) piles that are used in almost any type of ground to transfer structural load to competent bearing strata. Micropiles are easily installed in restricted access and limited headroom situations.
Also known as minipiles, pin piles, root piles, pipe piles, etc.
2
Typical Micropile Program Involves
Drilling holes, 2”-12”+ diameter
The construction of a pile shaft consisting of high-strength steel pipes or steel bars
The filling of the hole with high strength cement grout
MicropilesDrilled and Grouted Steel Pipe Piles
Micropile Types
Soil Piles• Type S-1 – Composite Pile
• Type S-2 – Full Length Steel Pipe
Rock Piles• Type R-1 – Composite Pile
• Type R-2 – Full Length Steel Pipe
3
Micropile TypesFounded inDense Soils
Founded in Rock
S-1 S-2 R-1 R-2
Micropile Installation Process
ConstructionSequenceS-1 Pile
Drill
Grout
Install reinforcement
Pressure Grout
4
Construction SequenceR-1 Pile
Drill casing to rock
Drill rock socket
Grout
Install reinforcement
Micropiles –Typically Used For:
New Construction
Underpinning Existing Foundations
Limited Access or Headroom
Foundations where Obstructed Drilling is Required
Replacement for Drilled Shafts
Micropiles –Range of Ground Conditions:
Obstructions or Old Foundations
Variable Urban Fills
Karstic Limestone GeologyKarstic Limestone Geology
Glacial Till with Boulders
Mined Rock Geology
High Water Table
5
Micropiles –Physical Constraints to Installation:
Limited Overhead Clearance
Limited Access
Vibration Sensitive EnvironmentsVibration Sensitive Environments
Settlement Sensitive Projects
Close Proximity to Existing Structures
Micropiles –Piling Materials:
Steel Pipe•API N80
•Yield Strength = 80 ksi
•Special Machine Flush Joint Threads
High Strength Steel Reinforcing BarsHigh Strength Steel Reinforcing Bars•Grade 75, 80, 95 or 150
Grout•Neat Cement
•Water / Cement Ratio = 0.45
•Strength = 4000 psi
3. Structural Design
Components• Cased length
• Uncased length
• Grout to steel bond
• Transitions between reinforcement types
• Strain compatibilityp y
• Casing or bar splice and connection
• Footing connection
6
Structural Design (Internal):
Grout & steel Grout: 0.25-0.4*f’c{
Typical range of code allowable stresses(ASD):
Transfer zone (plunge)
Bond zone
Steel: 0.3-0.47*fy
{{
Connection Details
Shear transfer from grout
Bearing plate
Shear rings
Bearing Plate
Stiffener
Hewlett Packard Corvallis, ORSeismic Upgrade Connection
7
Micropiles –Geotechnical Aspects of Piles:
Friction Bond – Soil or Rock!
Compression and Tension Loads
20 – 500+ tons Working Load20 500 tons Working Load
Lateral Load Capacity: 5 – 15 tons
Battering is not a problem
MicropilesMicropiles
for thefor the
SpalationSpalation Neutron Source Neutron Source FACILITYFACILITY
OAK RIDGE, TENNESSEEOAK RIDGE, TENNESSEE
Hayward Baker/Nicholson JVHayward Baker/Nicholson JV
SITEOak Ridge
NashvilleKnoxville
Chattanooga
8
Y-12
OAK RIDGE
SITEETT Park(ORGDP)
ORNL
- Lawrence Berkeley
Los Alamos/Jefferson
- Oak Ridge
- Brookhaven
Argonne/Oak Ridge
Project Information
9
Project Scope
• Layers of weathered rock, soil filled cavities • Anticipated depths ranged from 40 to 200 ft. • Owner required three drilling operations
186 l d d h d l• 186 calendar day schedule
Project Scope
• Total of 1087 -- 12 inch dia. Minipiles in bid• 400 kip compression & tension capacity• 60 kip lateral load • Install four No 6 rebar w/#3 cage - top 8 ftInstall four No. 6 rebar w/#3 cage top 8 ft.• Install ten feet into bedrock in karst terrain
Alternate Bid Submitted
• 9-5/8 in. dia. w/0.545 in. wall to full depth
• 11-7/8 in dia. w/0.534 in. wall upper 20 ft.
• Single rebar of adequate size
• Two predrill rigs for open hole drilling
• Two drill rigs for installation of pipe
15
Pipe Installation
Completed Pile prior to
Rebar Extension
Pile Load Tests• Compression Tests - 4 planned
(4 test & 1 production pile conducted) 800 Kips
• Tension Tests 2 planned (2 conducted) • Tension Tests - 2 planned (2 conducted) 800 Kips
• Lateral Tests - 2 planned (2 conducted) 60 Kips
17
Compression Test C-3B
0
0.2
0.4
0.6
0 100 200 300 400 500 600 700 800 900
Load (kips)
es)
Pile Butt Deflection
Telltale Deflection
Load (kips)
Compression Test C-3B
0.8
1
1.2
1.4
1.6
Def
lect
ion
(in
ch
Deflection
Project Challenges
19
Rebar Forest
PROJECT ANALYSIS
• Projected No. of Piles ------ 1,087
• Actual No. of Piles ---------- 937
• Projected Drilling Footage - 113,500
• Actual Drilling Footage ----- 95,240
• Projected Grout Qty. (cyd) - 13,500
• Actual Grout Qty. (cyd) ----- 10,560
20
GKN Aerospace Press Mat FoundationSt. Louis, Missouri
A new machining press with movable static loads required a thick concrete mat supported on many lightly loaded friction piles
The pile section provided by HBI satisfied the structural engineer’s specifications for deflection
GKN owned Hayward Baker
until 1990!
GKN Aerospace Press Mat FoundationSt. Louis, Missouri
Subsurface Exploration Location Sketch
21
Boring Log
Log of CPT
Micropiles were installed using DK50 and Klemm 708 rigs working in limited headroom
22
Load Test Set-up and Reaction Frame
GKN Aerospace Press Mat FoundationSt. Louis, MissouriLoad Test
The End
Q ti ?Questions?
10/28/2009
1
AUGER CAST PILESAUGER CAST PILES
1
Richard W. Stephenson, Ph.D., P.E.Richard W. Stephenson, Ph.D., P.E.
AugerAuger--Cast PilesCast Piles
Also Known As:Also Known As:–– Augered Pressure Grouted Pile (APG)Augered Pressure Grouted Pile (APG)–– Augered CastAugered Cast--inin--Place PilesPlace Piles
2
–– Continuous Flight Auger PilesContinuous Flight Auger Piles–– Intruded Mortar PilesIntruded Mortar Piles–– Auger PilesAuger Piles–– Grouted Bored PilesGrouted Bored Piles–– Augered GroutAugered Grout--Injected PilesInjected Piles
10/28/20093
10/28/2009
2
AugerAuger--Cast PilesCast Piles
0.3 to 0.9 m (12 to 36) Inches Diameter
Up to 30 m (100 feet) Deep
4
p ( ) p
Capacities as for Driven Piles of Same Size
Single pilesSingle piles–– Sound wallSound wall–– Light poleLight poleLight poleLight pole
GroupsGroups–– BridgesBridges–– Etc.Etc.
10/28/2009 5
ReinforcementReinforcement
Confined to upper 10 to 15 m (33Confined to upper 10 to 15 m (33--50 ft)50 ft)Occasionally full length reinforcementOccasionally full length reinforcement
10/28/2009 6
10/28/2009
3
Differences between ACIP and Differences between ACIP and drilled shaftsdrilled shafts
The main difference is that the use of The main difference is that the use of casing or slurry to temporarily support casing or slurry to temporarily support the hole is avoided.the hole is avoided.
Drilling the hole in one continuous Drilling the hole in one continuous process is faster than drilling a shaft process is faster than drilling a shaft excavation,excavation,
10/28/2009 7
The torque requirement to install the The torque requirement to install the continuous auger is high compared with continuous auger is high compared with a conventional drilled shaft of similar a conventional drilled shaft of similar diameter; therefore, diameter; therefore,
The diameter and length of ACIP piles The diameter and length of ACIP piles g pg pare generally less than drilled shafts.are generally less than drilled shafts.
The use of a continuous auger for The use of a continuous auger for installation also limits ACIP piles to soil installation also limits ACIP piles to soil or very weak rock profilesor very weak rock profiles
10/28/2009 8
Differences between ACIP and Differences between ACIP and driven pilesdriven piles
Noise and vibration due to pile driving Noise and vibration due to pile driving are minimizedare minimized
ACIP piles also eliminate splices and ACIP piles also eliminate splices and cutoffs.cutoffs.
Soil heave due to driving can be Soil heave due to driving can be eliminatedeliminated
10/28/2009 9
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4
A disadvantage of ACIP piles A disadvantage of ACIP piles compared to driven piles is that compared to driven piles is that the available QA methods to verify the available QA methods to verify the structural integrity and pile the structural integrity and pile bearing capacity for ACIP piles are bearing capacity for ACIP piles are less reliable than those for driven less reliable than those for driven pilespilespiles.piles.
Another disadvantage of ACIP piles Another disadvantage of ACIP piles is that ACIP piles generate soil is that ACIP piles generate soil spoils that require collection and spoils that require collection and disposal.disposal.
10/28/2009 10
Construction Techniques Construction Techniques and Materialsand Materials
10/28/2009 11
Drill RigsDrill RigsCrane Crane MountedMountedContinuousContinuous--flight hollowflight hollow--stem augerstem augerCrowdCrowdCrowd Crowd limited to limited to total weight total weight of gearbox, of gearbox, augers above augers above ground and ground and soil on auger soil on auger flightsflights
10/28/2009 12
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5
torque capacities torque capacities for cranefor crane--attached rigs attached rigs range from 20 to range from 20 to 120 kN120 kN--m m (15,000 to (15,000 to 90,000 ft90,000 ft--lbs);lbs);
7 to 50 kN7 to 50 kN mm7 to 50 kN7 to 50 kN--m m (20,000 to (20,000 to 36,000 ft36,000 ft--lbs) lbs) are most are most common for common for private private commercial commercial work.work.
10/28/2009 13
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Hydraulic Rig
10/28/2009 15
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8
10/28/2009 22
Grout or Concrete?Grout or Concrete?
Grout mixes are sometimes preferred for easier Grout mixes are sometimes preferred for easier insertion of steel reinforcement into the pile;insertion of steel reinforcement into the pile;
Grout mixes tend to be more fluid and have Grout mixes tend to be more fluid and have greater workability; andgreater workability; andgreater workability; andgreater workability; and
Grout mixes tend to be easier to pump, and Grout mixes tend to be easier to pump, and many contractors, who have historically used many contractors, who have historically used grout mixes, have grout pumps and equipment grout mixes, have grout pumps and equipment that may not be suitable for use with concrete.that may not be suitable for use with concrete.
10/28/2009 23
Grout will generally have a higher unit cost than Grout will generally have a higher unit cost than concrete;concrete;
Grout will tend to have a slightly lower elastic Grout will tend to have a slightly lower elastic modulus than concrete; andmodulus than concrete; and
Grout will tend to be less stable within the hole Grout will tend to be less stable within the hole when drilling through extremely soft soils (such as when drilling through extremely soft soils (such as organic clays or silt).organic clays or silt).
10/28/2009 24
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9
10/28/2009 25
Wider acceptance of ACIP Piles in Wider acceptance of ACIP Piles in commercial rather than commercial rather than
transportationtransportationSimple foundation requirements: a large number of Simple foundation requirements: a large number of piles are commonly used in a compact area primarily piles are commonly used in a compact area primarily to support large concentrated dead loads.to support large concentrated dead loads.
S d f i t ll ti f ACIP il th ilS d f i t ll ti f ACIP il th ilSpeed of installation of ACIP piles over other pile Speed of installation of ACIP piles over other pile types.types.
Increased use of designIncreased use of design--build contracting in private build contracting in private work, in which contractors are highly motivated work, in which contractors are highly motivated toward speed, economy, and innovations to those toward speed, economy, and innovations to those means.means.
10/28/2009 26
Increased requirements to minimize noise and Increased requirements to minimize noise and vibrations from pile installation in heavily populated vibrations from pile installation in heavily populated areas.areas.
A reluctance by many owners to utilize ACIP piles A reluctance by many owners to utilize ACIP piles because of concerns about quality control and because of concerns about quality control and structural integrity.structural integrity.
The typical demand on bridges for uplift and lateral The typical demand on bridges for uplift and lateral load capacity, scour considerations, and/or seismic load capacity, scour considerations, and/or seismic considerations, require pile diameters and possibly considerations, require pile diameters and possibly lengths up to a range not commonly used with ACIP lengths up to a range not commonly used with ACIP piles in private commercial work in U.S. markets.piles in private commercial work in U.S. markets.
10/28/2009 27
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10
Advantages and Advantages and Limitations of ACIP PilesLimitations of ACIP Piles
10/28/2009 28
Limitations of ACIP PilesLimitations of ACIP Piles
Favorable Geotechnical Favorable Geotechnical ConditionsConditions
Medium to very stiff clay soils.Medium to very stiff clay soils.–– clays are generally stable during drilling clays are generally stable during drilling
and less subject to concerns about soil and less subject to concerns about soil i i d i d illii i d i d illi
10/28/2009 29
mining during drilling.mining during drilling.
Cemented sands or weak limestoneCemented sands or weak limestone
Residual soils.Residual soils.
Medium dense to dense silty sands and Medium dense to dense silty sands and wellwell--graded sands.graded sands.
Rock overlain by stiff or cemented Rock overlain by stiff or cemented deposits.deposits.
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11
Unfavorable Geotechnical Unfavorable Geotechnical ConditionsConditions
Very soft soils.Very soft soils.
Loose sands or very clean uniformly Loose sands or very clean uniformly graded sands under groundwatergraded sands under groundwater
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graded sands under groundwatergraded sands under groundwater
Geologic formations containing voids, Geologic formations containing voids, pockets of water, lenses of very soft pockets of water, lenses of very soft soils, and/or flowing water.soils, and/or flowing water.
Hard soil or rock overlain by soft soil or Hard soil or rock overlain by soft soil or loose, granular soil.loose, granular soil.
SandSand--bearing stratum underlying stiff bearing stratum underlying stiff clay.clay.
Highly variable ground conditions.Highly variable ground conditions.
Conditions requiring penetration of very Conditions requiring penetration of very hard strata.hard strata.
10/28/2009 32
Ground conditions requiring Ground conditions requiring uncommonly long piles.uncommonly long piles.
Ground conditions with deep scour or Ground conditions with deep scour or liquefiable sand layers.liquefiable sand layers.
10/28/2009 33
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12
Project Conditions Project Conditions Affecting the Selection and Affecting the Selection and
Use of ACIP PilesUse of ACIP PilesUse of ACIP PilesUse of ACIP Piles
10/28/2009 34
Projects where speed of installation is Projects where speed of installation is important.important.
Batter Piles Required.Batter Piles Required.
P j t h l b f ilP j t h l b f ilProjects where large numbers of piles Projects where large numbers of piles are required.are required.
Low headroom conditions.Low headroom conditions.
10/28/2009 35
Secant or tangent pile walls up to 10 m Secant or tangent pile walls up to 10 m (33 ft) of exposed wall height.(33 ft) of exposed wall height.
Sound walls in favorable soil conditionsSound walls in favorable soil conditions
PilPil t d b k tt d b k tPilePile--supported embankments.supported embankments.
10/28/2009 36
10/28/2009
14
EVALUATION OF STATIC EVALUATION OF STATIC CAPACITY OFCAPACITY OF
AUGEREDAUGERED CASTCAST ININ PLACEPLACEAUGEREDAUGERED--CASTCAST--ININ--PLACE PLACE PILESPILES
10/28/2009 40
General Design EquationGeneral Design Equation
where,– qp = ultimate unit
end bearing capacity
10/28/2009 41
end bearing capacity,– Ab = cross-sectional
area of the pile base,– fs = ultimate unit
friction capacity, and– As = perimeter area
of the pile.
ssbpultv AfAqQ ⋅+⋅=,
The behavior of ACIP piles falls somewhere between that of drilled
10/28/2009 42
somewhere between that of drilled shafts and driven piles
10/28/2009
15
ZeladaZelada and Stephenson and Stephenson (2000)(2000)
SCOPE OF WORKSCOPE OF WORK
This study compared computed theoretical load capacity using eight different published
10/28/2009 43
p y g g ptechniques, with the results from a field load test database of ACIP piles constructed in cohesionless soils. Recommendations were made regarding the design approach most appropriate for these foundations and the best procedure for estimating ultimate capacity from pile load tests.
Auger Cast Piles Auger Cast Piles –– Sand Sand ––Tip CapacitiesTip Capacities
Empirical formulas based on sixty load tests Empirical formulas based on sixty load tests on piles from 12 to 24 inches diameteron piles from 12 to 24 inches diameter
Embedments of from 15Embedments of from 15--85 feet85 feet
44
Embedments of from 15Embedments of from 15 85 feet85 feet
Capacity is based on the auger diameter, not Capacity is based on the auger diameter, not the eventual constructed pile diameter.the eventual constructed pile diameter.
FHWA 1999 FHWA 1999
tsfNpq 759.1 ≤=Neely (1991)
10/28/2009 45
75Nfor 3.4)(
75N0for 6.0 )(
6060
6060
>=
≤≤=
NMPaq
Ntsfq
p
p
N60 is the SPT-N value at 60% efficiency near the tip of the pile (1 diameter above to 2 or 3 diameters below the pile tip)
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16
Auger Cast Piles Auger Cast Piles –– Sand Sand ––Side CapacitiesSide Capacities
10/28/2009 46
Side CapacitiesSide Capacities
Neely (1991)
tsfpf os 4.1' ≤⋅= β
10/28/2009 47
Wright and Reese (1978) (McVay et al., 1994)
tsfKpf 61tan' ≤= φ
Where– Ks is taken as 1.1, – p’o is the
ff ti
10/28/2009 48
tsfKpf ss 6.1tan0 ≤= φ average effective stress along the length of the pile and
– φ is the angle of internal friction of the soil
tsfNdq 403
205.0
≤⋅=
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17
Reese and O’Neill (FHWA, 1988)
The end bearing is taken as 0.6N (tsf) at the
2.125.0135.05.1tan 5.0 ≤≤−==⋅ ββφ zK
10/28/2009 49
The end bearing is taken as 0.6N (tsf) at thetip, for N values less than 75.For N values greater than 75, the unit endbearing is assumed to be a constant 45 tsf (4MPa).
RESULTSRESULTS
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New EquationsNew EquationsZeladaZelada and Stephenson (2000)and Stephenson (2000)
5.0108.02.1 z−=βf 'β
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tsfNqb 757.1 ≤⋅=
os pf '⋅= β
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18
TIP RESISTANCETIP RESISTANCE
200
250
300 350
400
Tip stan
Meyerhof (Driven Piles)
represent derived values from measured loads.
10/28/2009 52
0
50
100 150
200
0 20 40 60 80 100
SPT N-value
sf)
Neely
Reese & O'Neill
Avg. Unit Tip = 1.7N
COHESIVE SOILCOHESIVE SOIL
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American Petroleum Institute (16) Cohesive Soil The shaft friction in cohesive soil can be calculated at any point along the pile by the following:
fs = αcu (24)
where α = a dimensionless factor cu = undrained shear strength of the soil at the point in
10/28/2009 54
question α = 0.5ψ-0.5 for ψ ≤ 1 (25) α = 0.5ψ-0.25 for ψ > 1 (26) with the constraint that α ≤ 1.0. ψ = cu/σv’ for the point of interest (27) where σv’ = effective overburden pressure at the point in question.
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19
FHWA 1999FHWA 1999
51/f550 ≤= us
P
cf α
10/28/2009 55
5.1/cfor 55.0 u ≤= aPαPa = atmospheric pressure
The unit point resistance for piles in bearing in cohesive soil can be calculated by the following
10/28/2009 56
cohesive soil can be calculated by the following.qp = 9cu
FHWA
Coyle et. al
API
Unconservative Conservative
10/28/2009 57
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75
Measured/Predicted Load Ratio
LPC
German Standard
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20
AUGER CAST PILESAUGER CAST PILESQA/ACQA/AC
10/28/2009 58
Richard W. Stephenson, Ph.D., P.E.Richard W. Stephenson, Ph.D., P.E.
Recommended RecordsRecommended Records
1. Pile location and plumbness;
2. Ground surface elevation;
59
3. Pile toe (bottom) depth/elevation;
4. Depth/Elevation of top of grout/concrete;
5. Pile length;
6. Auger diameter;
7. Details of the reinforcing steel (number, size, and grade of longitudinal bars, size andspacing of transverse steel; outside diameter and length of cage);
8. Flow cone efflux time and volume of grout placed,
60
g p ,or slump and volume of concreteplaced;
9. Theoretical volume of excavation (theoretical diameter = diameter of auger);
10. Depth/Elevation to which reinforcing steel was placed;
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21
11. Date/Time of beginning of drilling;
12. Date/Time of completion of drilling;
13. Date/Time grout or concrete was mixed;
14. Date/Time ready-mix grout or concrete truck i d t j t it d i f ll
61
arrived at project site, and copies of allgrout or concrete batch tickets used for the pile construction;
15. Date/Time of beginning of grout or concrete pumping;
16. Date/Time of completion of grout or concrete pumping;
17. Date/Time of placement of reinforcing steel;
18. Weather conditions, including air temperature, at time of grout or concrete placement;
19. Identification of all grout or concrete samples taken from the pile;
20. All other pertinent data relative to the pile installation; and
21. All readings made by the automated measuring and recording equipment to include as a minimum:
a. auger rotation vs. depth for every 0.6-m (2-ft) increment, or less, of pile advancement during the drilling process, and during placement of grout orconcrete (if auger is rotated during this placement);concrete (if auger is rotated during this placement); and
b. volume of grout or concrete placed versus depth of outlet orifice for every 0.6-m(2-ft) increment, or less, of pile placed;
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22
c. Average maximum and minimum pump stroke pressures at ground level for every0.6-m (2-ft) increment, or less, of pile placed;
d. Average maximum and minimum pump stroke pressure at or near the auger headfor every 0.6-m (2-ft) increment, or less, of pile placed, if directed by the engineer; andy g ;
e. Additionally, the engineer may also specify that the torque and crowd force (downward thrust on auger) measurements be made at every 0.6-m (2-ft)increment, or less, of pile advancement during the drilling process.
PERFORMANCE PERFORMANCE MONITORING AND MONITORING AND CONTROL DURING CONTROL DURING CONSTRUCCTIONCONSTRUCCTION
Past PracticePast Practice
••Importance of a skilled operatorImportance of a skilled operator
••Use of visual observations of the Use of visual observations of the drillingdrilling
••Crude estimates of grout/concrete Crude estimates of grout/concrete pumpedpumped
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23
MONITORING AND MONITORING AND CONTROL OF THE CONTROL OF THE DRILLING PHASEDRILLING PHASEDRILLING PHASEDRILLING PHASE
Goals of Monitoring and Control:Goals of Monitoring and Control:
•Ensure that excessive flighting of soil does not occur and
•The appropriate level of soil displacement occurs
General Guidelines for Auger Penetration Rate for CFA Piles
Soil Type Rate of Penetration(Revolutions per Auger Pitch)
Clay soils 2 to 3
Cohesionless soils 1.5 to 2
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24
••In the Manual Control System:In the Manual Control System:
•Auger speed is predetermined by the gearbox setting
•The depth of penetration is monitored by direct observation of the to of the auger in the leads, and
•The rate of penetration is observed using a stopwatch.
Better method:Better method:
•Depth encoder and revolution counter to monitor and display the rate of penetration graphically in units of revolutions per meter of penetration
•Use with hydraulic fixed mast drilling equipment that allows control of crowd, torque and speed of revolution.
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25
Crane Mounted:Crane Mounted:
•Depth encoder and a clock to monitor the rate of penetration.
•The speed of auger rotation is controlled via the bgearbox.
Monitoring and Control of the Monitoring and Control of the Grouting/Concreting PhaseGrouting/Concreting Phase
••Perhaps the most important aspect of QA/QC Perhaps the most important aspect of QA/QC for ACIP Pilesfor ACIP Piles
••Objective: Adequate grout or concrete be Objective: Adequate grout or concrete be delivered to the discharge point of the auger at delivered to the discharge point of the auger at the proper pressure.the proper pressure.
••Both pressure and volume must be monitored Both pressure and volume must be monitored as a function of auger depth.as a function of auger depth.
••Monitor the extraction of the auger.Monitor the extraction of the auger.
••The lift speed of the auger must be controlled The lift speed of the auger must be controlled so that the proper volume of concrete is so that the proper volume of concrete is delivered under sufficient pressure. delivered under sufficient pressure.
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26
••Observe and document:Observe and document:••Position of the auger tipPosition of the auger tip••Lifting speedLifting speed••Volume of grout/concrete deliveredVolume of grout/concrete delivered••Pressure with which the grout/concrete is Pressure with which the grout/concrete is delivered.delivered.
The manual method of monitoring and documenting The manual method of monitoring and documenting the grouting/concrete operation involves the the grouting/concrete operation involves the following:following:
• the position of the auger tip is monitored visually by observing the height of the augerin the leads;
• the lifting speed is controlled by the operator by feel and by observing the height ofthe auger in the leads while timing the withdrawal using a stopwatch;
• the volume of grout is measured by estimating the volume per stroke of the pump, and by manually counting the pump strokes; and
• the pressure with which the grout is p gdelivered is monitored by a gauge in the line near the pump.
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27
The system recommended for transportation projects includes automated monitoring of the augerposition; volume of grout/concrete that is delivered; pressure with which it is delivered; and rotation and lifting speed of the auger. Such system should provide the following:
• the position of the auger tip [monitored automatically by a position sensor ;
• the volume of grout [measured by an in-line flowmeter that provides a reliable and accurate measure of the grout/concrete that is delivered in real time];
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28
•the pressure with which the grout/concrete is delivered [monitored using a gauge in theline near the swivel at the top of the auger, or in the auger itself near the tip (latter option is better)];
• the rotation of the auger [monitored by a sensor];
• the lifting speed [controlled by the operator based on real time observation of the control parameters notedreal time observation of the control parameters noted above, displayed graphically in the cab of the rig, and compared to target values]; and
• the entire operation [recorded as a part of the documentation process].
CONCLUSIONSCONCLUSIONSACIP Piles are becoming a dominant ACIP Piles are becoming a dominant player in the Midwestplayer in the Midwest
Resistance to use is primarily related to Resistance to use is primarily related to p yp ythe lack of conventional QA/QC the lack of conventional QA/QC proceduresprocedures
Design equations existDesign equations exist
84
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29
ReferencesReferencesDan A. Brown, Ph.D., P.E., Steven D. Dapp, Ph.D., P.E., W. Robert Dan A. Brown, Ph.D., P.E., Steven D. Dapp, Ph.D., P.E., W. Robert Thompson, III, P.E., and Carlos A. Lazarte, Ph.D., P.E., GEOTECHNICAL Thompson, III, P.E., and Carlos A. Lazarte, Ph.D., P.E., GEOTECHNICAL ENGINEERING CIRCULAR NO. 8 Design and Construction of Continuous ENGINEERING CIRCULAR NO. 8 Design and Construction of Continuous Flight Auger (CFA) PilesFlight Auger (CFA) PilesBustamante, M., and Gianeselli, L. (1981). “Portance Réele et Portance Bustamante, M., and Gianeselli, L. (1981). “Portance Réele et Portance Calculée des Pieux Isolés Sollicités Verticalement,” Revue Francaise de Calculée des Pieux Isolés Sollicités Verticalement,” Revue Francaise de Geotéchnique, No. 16, Presses de l’ Geotéchnique, No. 16, Presses de l’ ENPC, France.ENPC, France.Bustamante, M., and Gianeselli, L. (1982). “Pile Bearing Capacity by Bustamante, M., and Gianeselli, L. (1982). “Pile Bearing Capacity by Means Means of of Static Penetrometer Static Penetrometer CPT,” In Proceedings of the 2nd CPT,” In Proceedings of the 2nd
10/28/2009 85
, g, gEuropean Symposium on European Symposium on Penetration TestingPenetration Testing. Amsterdam, pp. 493. Amsterdam, pp. 493––500.500.Chin, F.K. (1970). “Estimation of the Ultimate Load of Piles not Carried Chin, F.K. (1970). “Estimation of the Ultimate Load of Piles not Carried to Failure,” Proceedings of the Second Southeast Asian Conference on to Failure,” Proceedings of the Second Southeast Asian Conference on Soil Engineering, Singapore, Vol. 1, pp. 81Soil Engineering, Singapore, Vol. 1, pp. 81––90.90.Clemente, J.L.M., Davie, J.R., and Senapathy, H. (2000). “Design and Clemente, J.L.M., Davie, J.R., and Senapathy, H. (2000). “Design and Load Testing of Augercast Piles in Stiff Clay,” Geotechnical Special Load Testing of Augercast Piles in Stiff Clay,” Geotechnical Special Publication No. 100, Ed. By N. D. Dennis, R. Castelli, and M. W. O’Neill Publication No. 100, Ed. By N. D. Dennis, R. Castelli, and M. W. O’Neill (Eds.), ASCE, August, pp. 398(Eds.), ASCE, August, pp. 398––403.403.
Coleman, D.M. and Arcement, B.J. (2002). “Evaluation of Design Coleman, D.M. and Arcement, B.J. (2002). “Evaluation of Design Methods for Auger Cast Piles in Mixed Soil Conditions,” Proceedings of Methods for Auger Cast Piles in Mixed Soil Conditions,” Proceedings of the International Deep Foundations Congress 2002, February 14the International Deep Foundations Congress 2002, February 14--16, 16, 2002 Orlando, Florida; M.W. O’Neill and F.C. Townsend (Eds.), ASCE, 2002 Orlando, Florida; M.W. O’Neill and F.C. Townsend (Eds.), ASCE, pp. 1404pp. 1404––1420.1420.Coyle H. M., and Castello, R. R. (1981). “New Design Correlations for Coyle H. M., and Castello, R. R. (1981). “New Design Correlations for Piles on Sand,” Journal of the Geotechnical Engineering Division, ASCE, Piles on Sand,” Journal of the Geotechnical Engineering Division, ASCE, Vol. 106 No. GT7, pp. 965Vol. 106 No. GT7, pp. 965––986.986.Decourt, L. (2003). “Behaviour of a CFA Pile in a Lateric Clay,” Decourt, L. (2003). “Behaviour of a CFA Pile in a Lateric Clay,” Proceedings of the 4Proceedings of the 4thth International Geotechnical Seminar on Deep International Geotechnical Seminar on Deep Foundations on Bored and Auger Piles, BAP IV, Ghent, Belgium, pp. Foundations on Bored and Auger Piles, BAP IV, Ghent, Belgium, pp. 301301––308.308.DFI (2005). “Manual for Non Destructive Testing and Evaluation of DFI (2005). “Manual for Non Destructive Testing and Evaluation of Drilled Shafts”, Deep Foundations Institute, Chernauskas, L.E. (Ed.) Drilled Shafts”, Deep Foundations Institute, Chernauskas, L.E. (Ed.) Hawthorne, NJ.Hawthorne, NJ.Douglas, D. J. (1983). “Discussion on Paper 17Douglas, D. J. (1983). “Discussion on Paper 17--22: Case Histories,” 22: Case Histories,” Proceeding, Conference on Piling and Ground Treatment, Institution of Proceeding, Conference on Piling and Ground Treatment, Institution of Civil Engineering, London, pp. 283.Civil Engineering, London, pp. 283.
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Fleming, W.G.K. (1995). “The Understanding of Continuous Flight Fleming, W.G.K. (1995). “The Understanding of Continuous Flight Auger Piling, Its Monitoring and Control,” Proceedings, Institution of Auger Piling, Its Monitoring and Control,” Proceedings, Institution of Civil Engineers Geotechnical Engineering, Vol. 113, July, pp. 157Civil Engineers Geotechnical Engineering, Vol. 113, July, pp. 157––165. 165. Discussion by R. SmythDiscussion by R. Smyth--Osbourne and reply, Vol. 119, Oct., 1996, p. Osbourne and reply, Vol. 119, Oct., 1996, p. 237.237.Frizzi, R.P. and Meyer, M.E. (2000). “Augercast Piles: South Florida Frizzi, R.P. and Meyer, M.E. (2000). “Augercast Piles: South Florida Experience,” Geotechnical Special Publication No. 100, N. D. Dennis, R. Experience,” Geotechnical Special Publication No. 100, N. D. Dennis, R. Castelli, and M. W. O’Neill (Eds.), ASCE, August, pp. 382Castelli, and M. W. O’Neill (Eds.), ASCE, August, pp. 382––396.396.McVay, M., Armaghani, B, and Casper, R. (1994). “Design and McVay, M., Armaghani, B, and Casper, R. (1994). “Design and Construction of AugerConstruction of Auger--Cast Piles in Florida,” Transportation Research Cast Piles in Florida,” Transportation Research Record 1447 Design and Construction of Auger Cast Piles and OtherRecord 1447 Design and Construction of Auger Cast Piles and OtherRecord 1447, Design and Construction of Auger Cast Piles, and Other Record 1447, Design and Construction of Auger Cast Piles, and Other Foundation Issues, Washington, pp. 10Foundation Issues, Washington, pp. 10––18.18.Neely, W. J. (1991) “Bearing Capacity of AugerNeely, W. J. (1991) “Bearing Capacity of Auger--Cast Piles in Sand,” Cast Piles in Sand,” Journal of Geotechnical Engineering, ASCE, Vol. 117, No. 2, pp. 331Journal of Geotechnical Engineering, ASCE, Vol. 117, No. 2, pp. 331––345.345.O’Neill, M. W., Ata, A., Vipulanandan, C., and Yin, S. (2002). “Axial O’Neill, M. W., Ata, A., Vipulanandan, C., and Yin, S. (2002). “Axial Performance of ACIP Piles in Texas Coastal Soils,” Geotechnical Special Performance of ACIP Piles in Texas Coastal Soils,” Geotechnical Special Publication No. 116, Ed. by M. W. O’Neill and F. C. Townsend (Eds.), Publication No. 116, Ed. by M. W. O’Neill and F. C. Townsend (Eds.), ASCE, February, Vol. 1, pp. 1290ASCE, February, Vol. 1, pp. 1290––13041304
10/28/2009 87
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O’Neill, M. W., Vipulanandan, C., Ata, A., Tan, F. (1999). “Axial O’Neill, M. W., Vipulanandan, C., Ata, A., Tan, F. (1999). “Axial Performance of ContinuousPerformance of Continuous-- FlightFlight--Auger Piles for Bearing,” Final report Auger Piles for Bearing,” Final report to the Texas Department of Transportation, Report No. 7to the Texas Department of Transportation, Report No. 7--39403940--2, 2, August, 254 .August, 254 .O’Neill, M.W. and Reese, L.C. (1999). “Drilled Shafts: Construction O’Neill, M.W. and Reese, L.C. (1999). “Drilled Shafts: Construction Procedures and Design Methods,” FHWA Report No. IFProcedures and Design Methods,” FHWA Report No. IF--9999--025, Federal 025, Federal Highway Administration, Washington, D.C.Highway Administration, Washington, D.C.O’Neill, M.W., Vipulanandan, C., and Hassan, K. (2000). “Modeling of O’Neill, M.W., Vipulanandan, C., and Hassan, K. (2000). “Modeling of Laterally Loaded ACIP Piles in Overconsolidated Clay,” Geotechnical Laterally Loaded ACIP Piles in Overconsolidated Clay,” Geotechnical Special Publication No. 100, N. D. Dennis, R. Castelli, and M. W. O’Neill Special Publication No. 100, N. D. Dennis, R. Castelli, and M. W. O’Neill (Eds.), ASCE, August, pp. 382(Eds.), ASCE, August, pp. 382––396.396.(Eds.), ASCE, August, pp. 382(Eds.), ASCE, August, pp. 382 396.396.Reese, L. C., and O’Neill M. W. (1988). “Drilled Shaft: Construction Reese, L. C., and O’Neill M. W. (1988). “Drilled Shaft: Construction Procedures and Design Methods,” FHWAProcedures and Design Methods,” FHWA--HIHI--8888--042, Federal Highway 042, Federal Highway Administration, Washington, D.C.Administration, Washington, D.C.Viggiani, C. (1993) “Further Experiences with Auger Piles in Naples Viggiani, C. (1993) “Further Experiences with Auger Piles in Naples Area,” Proceedings of the 2nd International Geotechnical Seminar on Area,” Proceedings of the 2nd International Geotechnical Seminar on Deep Deep
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Zelada, G. A., and Stephenson, R. W. (2000). “Design Methods for Zelada, G. A., and Stephenson, R. W. (2000). “Design Methods for Auger CIP piles in Compression,” New Technological and Design Auger CIP piles in Compression,” New Technological and Design Developments in Deep Foundations, ASCE Geotechnical Special Developments in Deep Foundations, ASCE Geotechnical Special Publication No. 100, N. D. Dennis, R. Castelli and M. W. O’Neill (Eds.), Publication No. 100, N. D. Dennis, R. Castelli and M. W. O’Neill (Eds.), ASCE, August, pp. 418ASCE, August, pp. 418––432.432.
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THANK YOUTHANK YOU
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11/1/2009
1
Geotechnical Earthquake Engineeringfor the New I-70 Mississippi River Bridge
Youssef M A Hashash & Scott M Olson
University of Illinois at Urbana-Champaign 1
Youssef M. A. Hashash & Scott M. Olson
Department of Civil and Environmental Engineering
University of Illinois at Urbana-Champaign
Fall Technical Seminar
ASCE Geotechnical Group – St. Louis
October 30, 2009
AcknowledgementsAcknowledgements
• Dr. Norm Abrahamson
• Mr. Steve Hague, structural design team, and geotechnical design team, HNTB Corporation
University of Illinois at Urbana-Champaign 3
OutlineOutline
• Background
• Site investigation
• Seismic hazard analysis & conditional mean spectrum
University of Illinois at Urbana-Champaign 4
• Nonlinear site response analysis
• Liquefaction & seismic stability analyses
• Concluding remarks
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BackgroundBackground
• New cable-stayed structure to divert I-70 traffic north of Poplar Street bridge
• 6,460 ft of structure including Illinois approach, main span (~1500 ft navigation channel), and Missouri approach
• 23 pier locations• Main span founded
University of Illinois at Urbana-Champaign 5
Main span founded on hydrauliccaissons
Artist’s rendering from HNTB
Earthquake ShakingEarthquake Shaking
Fault ruptureWave propagationlocal Ground motion and site effects
Permanent ground deformations: Ground FailureTsunamis & Ground FailureTransient ground deformations: site response
University of Illinois at Urbana-Champaign 6CEE 588, Lecture 01; © 2005 Y. M. A. Hashash &
Site InvestigationSite Investigation
• 42 exploratory borings at 23 pier locations
• Downhole geophysics performed at 10 boring locations
• 18 seismic piezocone penetration tests
University of Illinois at Urbana-Champaign 7
• Index, permeability, and strength testing for soils and rock
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3
General Subsurface ConditionsGeneral Subsurface Conditions
University of Illinois at Urbana-Champaign 8
Subsurface Conditions Subsurface Conditions –– Missouri approachMissouri approach
University of Illinois at Urbana-Champaign 9
Subsurface Conditions Subsurface Conditions –– Missouri alluviumMissouri alluvium
University of Illinois at Urbana-Champaign 10
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Subsurface Conditions Subsurface Conditions –– Illinois recent alluviumIllinois recent alluvium
University of Illinois at Urbana-Champaign 11
Subsurface Conditions Subsurface Conditions –– Illinois Illinois glaciofluvialglaciofluvial
University of Illinois at Urbana-Champaign 12
Subsurface Conditions Subsurface Conditions –– Limestone bedrockLimestone bedrock
University of Illinois at Urbana-Champaign 13
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Example design profile Example design profile –– SRSR--ILIL--22
University of Illinois at Urbana-Champaign 14
DETERMINISTIC HAZARD ANALYSIS (DHA): DETERMINISTIC HAZARD ANALYSIS (DHA): Scenario EarthquakeScenario Earthquake
University of Illinois at Urbana-Champaign 15
PROBABILISTIC SEISMIC HAZARD ANALYSIS PROBABILISTIC SEISMIC HAZARD ANALYSIS (PSHA)(PSHA)
University of Illinois at Urbana-Champaign 16
11/1/2009
6
Use Deaggregation to obtain M and R that has the highest contribution.
Memphis
DEAGGREGATIONDEAGGREGATION
University of Illinois at Urbana-Champaign 17
Contribution of M= 7.5 - 8events is dominant in NMSZ
Hazard at the margins Hazard at the margins -- NMSZNMSZ
University of Illinois at Urbana-Champaign 18
USGS
PSHA Response SpectraPSHA Response Spectra
0.4
0.5
0.6
ele
ratio
n (g
)
975UHS
M6 84th
M6 Med
M7.5 84th
M7.5 Med
0.2sec CMS
1.0sec CMS
5% in 50 yrs (975 yr) Hazard
0.4
0.5
0.6
ele
ratio
n (g
)
2500UHS
M6 84th
M6 Med
M7.5 84th
M7.5 Med
0.2sec CMS
1.0sec CMS
2% in 50 yrs (2475 yr) Hazard
University of Illinois at Urbana-Champaign 21
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
Sp
ect
ral A
cc
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
Sp
ect
ral A
cce
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DeaggregationDeaggregation--2500 2500 ((55%in %in 50 50 yrs)yrs)
University of Illinois at Urbana-Champaign 22
DeaggregationDeaggregation--2500 2500 ((55%in %in 50 50 yrs)yrs)
University of Illinois at Urbana-Champaign 23
DeaggregationDeaggregation--2500 2500 ((55%in %in 50 50 yrs)yrs)
University of Illinois at Urbana-Champaign 24
11/1/2009
8
Deterministic Seismic Hazard AnalysisDeterministic Seismic Hazard AnalysisBiBi--modal hazardmodal hazard
0.4
0.5
0.6
atio
n (g
)
975UHS
M6 84th
M6 Med
M7.5 84th
M7.5 Med
0.2sec CMS
1.0sec CMS
5% in 50 yrs (975 yr) Hazard
0.4
0.5
0.6
atio
n (g
)
2500UHS
M6 84th
M6 Med
M7.5 84th
M7.5 Med
0.2sec CMS
1.0sec CMS
2% in 50 yrs (2475 yr) Hazard
University of Illinois at Urbana-Champaign 25
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
Sp
ect
ral A
cce
lera
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
Sp
ect
ral A
cce
lera
PSHA PSHA vsvs DSHA: Can we reconcile?DSHA: Can we reconcile?
0.4
0.5
0.6
ele
ratio
n (
g)
975UHS
M6 84th
M6 Med
M7.5 84th
M7.5 Med
0.2sec CMS
1.0sec CMS
5% in 50 yrs (975 yr) Hazard
0.4
0.5
0.6
ele
ratio
n (
g)
2500UHS
M6 84th
M6 Med
M7.5 84th
M7.5 Med
0.2sec CMS
1.0sec CMS
2% in 50 yrs (2475 yr) Hazard
University of Illinois at Urbana-Champaign 26
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
Sp
ectr
al A
cce
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
Sp
ectr
al A
cce
What is Conditional Mean Spectrum What is Conditional Mean Spectrum (CMS) (CMS) slide from J. Baker Stanford Universityslide from J. Baker Stanford University
University of Illinois at Urbana-Champaign 27
11/1/2009
9
CMS (11) slide from J. Baker Stanford University
University of Illinois at Urbana-Champaign 37
PSHA PSHA vsvs DSHA: Can we reconcile?DSHA: Can we reconcile?
0.4
0.5
0.6
cele
ratio
n (g
)
975UHS
M6 84th
M6 Med
M7.5 84th
M7.5 Med
0.2sec CMS
1.0sec CMS
5% in 50 yrs (975 yr) Hazard
0.4
0.5
0.6
ele
ratio
n (g
)
2500UHS
M6 84th
M6 Med
M7.5 84th
M7.5 Med
0.2sec CMS
1.0sec CMS
2% in 50 yrs (2475 yr) Hazard
University of Illinois at Urbana-Champaign 38
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
Sp
ect
ral A
cc
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
Sp
ect
ral A
cc
CMS for Mississippi River BridgeCMS for Mississippi River Bridge
0.4
0.5
0.6
cele
ratio
n (
g)
975UHS
M6 84th
M6 Med
M7.5 84th
M7.5 Med
0.2sec CMS
1.0sec CMS
5% in 50 yrs (975 yr) Hazard
0.4
0.5
0.6
ele
ratio
n (
g)
2500UHS
M6 84th
M6 Med
M7.5 84th
M7.5 Med
0.2sec CMS
1.0sec CMS
2% in 50 yrs (2475 yr) HazardInstead of a single UHRS use two UHRS compatible CMS:
[email protected] ~ M=6 event
[email protected] ~ M=7.5 events
University of Illinois at Urbana-Champaign 39
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
Sp
ectr
al A
cc
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
Sp
ectr
al A
cc
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10
Background –– 11--D Site response D Site response modelingModelingmodelingModeling
1D Wave Propagation – Time Domain SolutionNumerical Solution:
1h11 ,G
Layer1
2
G
22 21 mm
22 32 mm
21m
11 c,k
22 c,k
k
2h
h
University of Illinois at Urbana-Champaign 41
i
n
22 ,G
ii ,G
nn ,G
3 33 ,G
EE ,G
iii hm
2nmSEEE VC nn c,k
33 c,k3h
nh
ih
Layer Properties
G: shear modulus: densityVS: shear wave velocityh: thickness
Equivalent Lumped Mass System
k: stiffnessc: viscous damping
Background –– 11--D ModelingD Modeling
1D Wave Propagation – Time Domain Solution
guIMuKuCuM
Equation of Motion:
University of Illinois at Urbana-Champaign 42
[C]: Damping matrix → Viscous DampingRayleigh DampingExhibit frequency dependent behavior
[M]: Mass matrix → Less uncertaintyStraightforward calculation
[K]: Stiffness matrix → Nonlinearity: Recalculated in each time stepUse of simplified models (i.e. Hyperbolic Model or Ramberg Osgood)Modulus reductionHysteretic Damping
Background –– 11--D ModelingD Modeling
1D Wave Propagation – Time Domain Solution
Gsec1
Gsec2
Initial L di
Modified Extended Hyperbolic Model
smo
s
mo
mo G
G
G
11
University of Illinois at Urbana-Champaign 43
Backbone Curve
LoadingCurve
SubsequentLoading & Unloading Curves
g
uMuKuCuM
Dynamic Equation :
rmo
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11
Issue 1:
Small Strain DampingSmall Strain Damping
University of Illinois at Urbana-Champaign 44
Small Strain – Viscous - Damping
g
uMuKuCuM
Dynamic Equation :
2
Stiffness proportional damping
Rayleigh Damping
1
0
1N
b
b
b KMaMC
Small Strain DampingSmall Strain Damping
University of Illinois at Urbana-Champaign 45
0
1
Full Rayleigh Damping
Simplified Rayleigh Damping
Extended Rayleigh
0 5 10 15 20 25 30 35Frequency (Hz)
Dam
ping
rat
io,
(%
)
Mass proportional damping
Frequency Independent
Over-damped
Under-damped
Small Strain Damping
Frequency Independent Damping Formulation to construct the damping matrix
11
021
11
0
21
0
1
N
b
N
b
bb
N
b
b
b aMaMKMaMC
University of Illinois at Urbana-Champaign 48
n
nn
N
b
bnb
nn
a
afaf
faf
2
2
12
4
12
4
1
21
2121
1
0
2
Small strain damping independent of the frequency → experimental results
11/1/2009
12
Issue 2:
University of Illinois at Urbana-Champaign 49
Large strain – hysteretic - damping
Large strain dampingLarge strain damping
0.0
0.2
0.4
0.6
0.8
1.0
0.0001 0.001 0.01 0.1 1
Shear strain - - [%]
G/G
0
MasingRules
-1.2
-0.8
-0.4
0.0
0.4
0.8
1.2
-1.2 -0.8 -0.4 0.0 0.4 0.8 1.2
/max,cycle
/m
ax,c
ycle
-1.2
-0.8
-0.4
0.0
0.4
0.8
1.2
-1.2 -0.8 -0.4 0.0 0.4 0.8 1.2
/max,cycle
/m
ax,c
ycle
-1.2
-0.8
-0.4
0.0
0.4
0.8
1.2
-1.2 -0.8 -0.4 0.0 0.4 0.8 1.2
/max,cycle
/m
ax,c
ycle
University of Illinois at Urbana-Champaign 50
0
5
10
15
20
25
30
35
40
0.0001 0.001 0.01 0.1 1
Shear strain - - [%]
Dam
ping
[%
]
Test Data Calculated Value
0
5
10
15
20
25
30
35
40
0.0001 0.001 0.01 0.1 1
Shear strain - - [%]
Dam
ping
[%
]
Test Data Calculated Value
Shear strain [%]
B
ADampingStrainSmalltotal
4
0
5
10
15
20
25
30
35
40
0.0001 0.001 0.01 0.1 1
Shear strain - - [%]
Dam
ping
[%
]
Test Data Calculated Value
0
5
10
15
20
25
30
35
40
0.0001 0.001 0.01 0.1 1
Shear strain - - [%]
Dam
ping
[%
]
Test Data Calculated Value
0
5
10
15
20
25
30
35
40
0.0001 0.001 0.01 0.1 1
Shear strain - - [%]
Dam
ping
[%
]
Test Data Calculated Value
DampingMismatch
Small strain Damping
Hysteretic Damping
s
G
1
0
Load Curve
Non Masing rule criteria
1
G0
mrev
New Fm)m
Large Strain Damping (Hysteretic)Large Strain Damping (Hysteretic)
University of Illinois at Urbana-Champaign 52
r
revs
r
m
revs
r
m
revs
r
rev
rev
m
GGG
F
112
1
22 00
0
Unload – Reload Curve
Load CurveUnload – Reload Curve
rev
11/1/2009
13
Non-Masing rule criteria
Use a reduction Factor MRDF:
3
1 m
pG
F
New Model
0.60
0.70
0.80
0.90
1.00on
Fac
tor
for
hyst
eret
ic D
ampi
ng
F(
) =
L
abo
rato
ry/
Mas
ing
Vucetic & Dobry 1991 -PI = 0 - Fit
Vucetic & Dobry 1991 -PI = 0 - Target
Seed & Idriss 1970 - SandMean - Fit
Seed & Idriss 1970 - SandMean - Target
Zhang et al. 2005 -Quaternary Soil PI = 0 -Fit
R2=0.99
R2=0.95
R2=0.99
R2=0.960.0
0.2
0.4
0.6
0.8
1.0
0 0001 0 001 0 01 0 1 1 10
G/G
o
0.0
0.2
0.4
0.6
0.8
1.0
0 0001 0 001 0 01 0 1 1 10
G/G
o
Large Strain Damping (Hysteretic)
University of Illinois at Urbana-Champaign 53
1 20
1 m
mF p pG
- Free Parameters- Fitting Methodology
0.40
0.50
0.01 0.1 1 10
Shear Strain - - [%]
Red
uctio
Zhang et al. 2005 -Quaternary Soil PI = 0 -Target
Zekkos et al. 2006 - 8-25%< 20mm - Fit
Zekkos et al. 2006 - 8-25%< 20mm - Target
0.0001 0.001 0.01 0.1 1 10
0
10
20
30
40
0.0001 0.001 0.01 0.1 1 10
Shear strain - - [%]
Dam
ping
[%
]
Sands Mean Limit - Seed & Idriss 1971Result Fitting MRDF
0.0001 0.001 0.01 0.1 1 10
0
10
20
30
40
0.0001 0.001 0.01 0.1 1 10
Shear strain - - [%]
Dam
ping
[%
]
Sands Mean Limit - Seed & Idriss 1971Result Fitting MRDF
ImplementationImplementation
DEEPSOIL
FrequencyDomain
Time Domain
1D Site Response Analysis (e.g. DEEPSOIL)http://www.illinois.edu/~deepsoil
University of Illinois at Urbana-Champaign 54
Linear
Equivalent Linear
Total Stress Effective Stress
Std. Hyperbolic Model (MR, MRD, MD)
New Hyperbolic Model(MRDF)
PWP ModelSand
PWP ModelClay
Linear
Non Linear
Implementation in DEEPSOILImplementation in DEEPSOIL
University of Illinois at Urbana-Champaign 55
http://www.illinois.edu/~Deepsoil/
11/1/2009
14
Large Strain Damping (Hysteretic)
Implementation in DEEPSOILImplementation in DEEPSOIL
University of Illinois at Urbana-Champaign 57
Fitting scheme
MR: Fitting Modulus Reduction Curve onlyMRD: Fitting Modulus Reduction and Damping Curve simultaneouslyMD: Fitting Damping Curve only MRDF: Fitting Modulus Reduction and Damping Curve simultaneously using the damping reduction factor. Non-Masing rule unload-reload criteria
V3.5 R17
60
50
40
30
20
10
0
ft)
0 500 1000 1500 2000Vs (ft/sec)
0 10 20 30 40PI
100120140160Unit weight (pcf)
0 4000 8000'vo (psf)
1 5 9 13OCR
0 500 1000 1500 2000su (psf)
alluvialmix
fine tomediumpoorly
d d
SP
alluvialmix
Typical Soil Profile Typical Soil Profile –– Illinois SideIllinois Side
University of Illinois at Urbana-Champaign 58
140
130
120
110
100
90
80
70
De
pth
(f
Vs = 6500 ft/s
Wxlimestone
Unwxlimestone
gradedsand (SP)
Site response for deep sectionsSite response for deep sectionsIllinois Profiles, Section SR-IL-2, SR-IL-3, SR-IL-42% in 50 yrs (2475 yr) Hazard
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
al A
cce
lera
tion
(g)
2475UHS(Rock)
0.2sec CMS(Rock)
Section 9
Section 7
Section 6
5% Damped Surface Response Spectra, 0.2 sec motion site response
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
al A
cce
lera
tion
(g)
975UHS(Rock)
0.2sec CMS(Rock)
Section 9
Section 7
Section 6
5% Damped Surface Response Spectra, 0.2 sec motion site response
Higher acceleration – Lower M Lower acceleration – Higher M
University of Illinois at Urbana-Champaign 59
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
0.4
0.5Spe
ctr
0.01 0.1 1 10Period (sec)
0
0.1
0.2
0.3
0.4
0.5Sp
ect
ra
Implication => very limited liquefaction v.s. extensive liquefaction without CMS
11/1/2009
15
Liquefaction Analysis ApproachLiquefaction Analysis Approach
• Triggering analysis– SPT using Youd et al. (2001) and checked with
Cetin et al. (2004)
– CPT using Robertson and Wride (1998) and checked with Moss et al (2006)
University of Illinois at Urbana-Champaign 60
checked with Moss et al. (2006)
• Lateral spreading analysis– Youd et al. (2002) and checked using Olson and
Johnson (2008) and Zhang et al. (2004)
Liquefaction Analysis ApproachLiquefaction Analysis Approach
• Liquefaction-induced settlement– SPT using Idriss and Boulanger (2008) and
checked using Tokimatsu and Seed (1987)
– CPT using Zhang et al. (2005) and checked using Ishihara et al (1992)
University of Illinois at Urbana-Champaign 61
Ishihara et al. (1992)
• Porewater pressure generation– Estimated using Marcuson and Hynes (1990)
Liquefaction evidenceLiquefaction evidence
• Liquefaction in St. Louis related to 1811-12 earthquakes was sparse
• Nuttli (1983) “mention of sand blow activity on
University of Illinois at Urbana-Champaign 69
of sand blow activity on floodplain
• Lateral spreading limit of about 175 km (Keefer 1984)
11/1/2009
16
Liquefaction evidenceLiquefaction evidence
• MMI ~ 7-8 from 1811-12 events
• Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse Damage
University of Illinois at Urbana-Champaign 70
with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned.
• Small water and sand ejections and localized lateral spreading adjacent to streams, canals, lakes, etc.
• A new concept of conditional mean spectra is introduced that bridges the gap between probabilistic and deterministic seismic hazard analysis
• Improved site response analysis procedures essential for reliable estimate of site effects
• The resulting site response and liquefaction analysis provided estimates of
ConclusionsConclusions
University of Illinois at Urbana-Champaign 71
The resulting site response and liquefaction analysis provided estimates of ground motions and ground response that are consistent with historical evidence.
• Significant impact on engineer design
THANK YOU
University of Illinois at Urbana-Champaign 72
THANK YOU