Date post: | 05-Aug-2015 |
Category: |
Engineering |
Upload: | cfpbolivia |
View: | 622 times |
Download: | 2 times |
www.fugro.comwww.loadtest.com
Deep Foundation Uncertainty and Bi-Directional Static Load
TestingPaul J. Bullock, PhD
Fugro Consultants Inc.Loadtest
www.fugro.comwww.loadtest.com
Deep Foundations
Precast Concrete
H-pile
Cast-in-Place
Pipe
Timber
www.fugro.comwww.loadtest.com
Which Deep Foundation Type?
• Type of Load (axial, lateral, torsion)
• Magnitude of Load• Project Size & Complexity• Site Conditions• Environmental Conditions• Local Availability & Price• Familiarity (engineer, client) & complacency• Foundation Cost Controlled by Uncertainty
(conservative design plus safety factor)
EngineeringDecisions
www.fugro.comwww.loadtest.com
Deep Foundation Design Uncertainty
• Site Variability• Axial, lateral, depth to bearing stratum• Strength, stiffness, test quality• Typically test < 0.01% of site
• Design Method: RN = Rside + Rbase
• Calibration, empiricism, codes, resistance or safety factors based on uncertainty
• Construction Quality• Contractor experience• Quality of supervision
www.fugro.comwww.loadtest.com
Reduce Cost by Reducing Uncertainty:
• Informed design (integrated investigation: geophysics + insitu testing + sampling)
• Design verification (static & dynamic testing)• Optimization (redesign)
• reduce length, size, number• change type (driven, drilled, anchor)• reduce cost and construction time ($$)• FLT’s experience - savings 5X test cost
• Quality control testing to assure performance & reduce remediation cost
www.fugro.comwww.loadtest.com
Integrated Ground Investigation
• Measure ground properties for design• More time characterizing site → more reliable design• Staged approach - progressively more targeted• Geophysical techniques provide overview • Insitu testing (CPT/DMT) calibrates geophysics, reduces
sampling disturbance and laboratory testing uncertainty• Insitu profiling (CPT) identifies thin layers missed by
drilling and sampling program• SPT not so great (drilling disturbance, variable energy)• Sampling and testing to characterize problem zones• Does not have to cost more, and can cost less• Preliminary pile tests included to prepare better plans?
www.fugro.comwww.loadtest.com
Horizontal Distance, m
Dep
th, m
Sand
Silty Clay
ClayeySand
Sounding Stopped at 33.5 m
Silty Clay
ClayeySand
0 2010CPT 03 qc, MPa
0
5
10
15
20
Sand
Clay
SiltyClay
Sand
ClayeySand
Refusal
0 2010CPT 01 qc, MPa
Dept
h, m
Tim
e, n
s
CPT 01
CPT 03
GPR Example
UF Insitu Test Site
www.fugro.comwww.loadtest.com
ElectroresistivityElectrical Resistivity Tomography Profile
www.fugro.comwww.loadtest.com
Electromagnetic ConductivityElectromagnetic Conductivity Profile
www.fugro.comwww.loadtest.com
Sand Overburden
Weathered Bedrock
More Competent
Bedrock
Bedrock Mapping
Seismic Refraction Tomography
www.fugro.comwww.loadtest.com
Insitu Cone Penetrometer Test (CPT)
• Robust push-in tool (ASTM D5778)
• Profiles penetration resistance
• Estimates soil type
• Undrained shear strength (clay)
• Friction angle (granular soils)
• Footing settlement, bearing pressure, pile capacity
• Compaction quality control
• Depth to cavities or bearing stratum
• Optimize borehole program
www.fugro.comwww.loadtest.com
CPT Platforms
www.fugro.comwww.loadtest.com
CPT Measurements / Soil Type
www.fugro.comwww.loadtest.com
Marchetti DilatometerPush-in Flat Blade
Minimizes Penetration Disturbance
(ASTM D6635)
Measurements:• Insitu Lateral
Stress• Modulus• Shear Strength• Depth Profile
(every 20 to 30 cm)Drill Rig
CPT Rig
www.fugro.comwww.loadtest.com
Marchetti DilatometerUses:• Settlement• Slope Stability• Lateral Stress
(walls, tunnels, excavations)
• Compaction Control• Dissipation Testing,
cH
www.fugro.comwww.loadtest.com
Reduce Cost by Reducing Uncertainty:
• Informed design (integrated investigation: geophysics + insitu testing + sampling)
• Design verification (static & dynamic testing)• Optimization (redesign)
• reduce length, size, number• change type (driven, drilled, anchor)• reduce cost and construction time ($$)• FLT’s experience - savings 5X test cost
• Quality control testing to assure performance & reduce remediation cost
www.fugro.comwww.loadtest.com
Top-down Static Load Test (ASTM D1143)
Design Optimization requires load to failure plus instrumentation
www.fugro.comwww.loadtest.com
Kentledge CollapseDue to platform/ground failure
from FPS Load Testing Handbook 2006
www.fugro.comwww.loadtest.com
Reaction Beam CollapseDue to tension bar failure
from FPS Load Testing Handbook 2006
www.fugro.comwww.loadtest.com
Bi-Directional Osterberg Cell Testing• Specialized jack in pile uses
bearing to mobilize side shear
• Developed by Dr. Jorj Osterberg and AEFC
• LOADTEST Inc. founded 1991 (purchased by Fugro in 2008)
• First “O-cell” tests on driven steel pipe piles 1987
• >2000 O-cell tests to date, mostly drilled shafts (300+/yr)
• ~ 30 driven piles since 1987 (12”-66”, 52 tons – 1,480 tons)
www.fugro.comwww.loadtest.com
P = F+Q
Conventional Test
F
Q
F
F1
Q
F2
Q
Osterberg Cell Test
O = F = Q = P/2 O = F1 = (F2+Q)
O
O
Pile Provides Reaction
Reaction System
P
www.fugro.comwww.loadtest.com
O-cell Features
• Robust for installation
• Aligned with pile axis
• Special seal for eccentricity
• Water used for hydraulic fluid
• Rated at 10,000 psi
• Calibrated by AEFC (NIST Traceability)
• Linear & Repeatable
• Strain gauges also confirm load
24” PHC Korea
www.fugro.comwww.loadtest.com
O-cell Instrumentation
• O-cell Pressure monitored by gauge and transducer
• Pile Top Movement
• O-cell Expansion Transducers
• O-cell Top Telltales
• Pile Bottom Telltales
• Embedded Strain Gauges
• Embedded Pile Compression Transducers
www.fugro.comwww.loadtest.com
Pumps
Drilled Shaft O-cell Test Setup
The contractor can demobilize, saving time and money
www.fugro.comwww.loadtest.com
Typ. O-cell Test – No Reference Beams
Leica digital levels monitor targets on top of shaft directly.Accuracy actually improved (Sinnreich, Simpson, DFI Journal, 2009).
www.fugro.comwww.loadtest.com
Driven Pile O-cell Test Setup• ASTM D1143
Quick Test (new standard coming)
• 20 Loads to failure
• 8 min load intervals (identify creep limit)
• All instruments monitored by datalogger
• Real-time load vs. deflection plot
• Reference beams replaced by electronic levels
www.fugro.comwww.loadtest.com
Load Transfer from O-cell & Strain Gauges
+465
+475
+485
+495
+505
+515
+525
+535
+545
+555
+565
+575
0 500 1,000 1,500 2,000 2,500
Elev
atio
n (
ft )
O-cell Load ( kips )
Top of Shaft
Bottom of Shaft
1L-1 1L-3 1L-5 1L-7 1L-9
S. G. Level 6
S. G. Level 5
S. G. Level 2
S. G. Level 3
O-cell Load
1L-11 1L-13 1L-171L-15 1L-19
www.fugro.comwww.loadtest.com
Side Shear from Load Transfer
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
0.0 0.5 1.0 1.5 2.0 2.5
Mob
ilize
d N
et U
nit S
ide
Shea
r ( k
sf )
Upward Average Shear Zone Displacement ( in )
S.G. Level 6 to Zero ShearS.G. Level 5 to S.G. Level 6S.G. Level 3 to S.G. Level 5S.G. Level 2 to S.G. Level 3O-cell to S.G. Level 2
www.fugro.comwww.loadtest.com
O-cell SizesO-cell Size Rated Capacity Max. Test Load
6” 100 tons 200 tons
9” 225 tons 450 tons
13” 438 tons 875 tons
16” 700 tons 1400 tons
20” 1125 tons 2250 tons
24” 1550 tons 3100 tons
26” 1950 tons 3900 tons
34” 3000 tons 6000 tons
• Cells typically welded to load plates• Cells can be grouped together• 6” stroke standard, 9” stroke available
www.fugro.comwww.loadtest.com
Drilled Shaft O-cell Plate Assembly
Weld Top and Bottom Plates to the O-cell
Weld O-cell Assembly to Rebar Cage
www.fugro.comwww.loadtest.com
Lifting the Cage and O-cell Assembly
Attach O-cell to Cage, lift carefully, place in shaft excavation
www.fugro.comwww.loadtest.com
Attaching O-cells to bottom plate
Multiple O-cell Assemblies
www.fugro.comwww.loadtest.com
Multiple O-cell Assemblies
Attaching O-cells to top plate
www.fugro.comwww.loadtest.com
Other O-cell Assemblies
O-cells placed at 2 levels to isolate distinct shaft elements
Rebar cage not required (save money and time)
www.fugro.comwww.loadtest.com
O-cells in CFA / ACIP Piles
www.fugro.comwww.loadtest.com
Maximum size/loads tested to date
Pile Diameter, mm 600 750 900 900
Pile Length, m 38 40 35 36
O-cell Diameter, mm 405 540 660 2x540
Mobilized Load, MN 17.5 32 32 46
O-cells in CFA / ACIP Piles
www.fugro.comwww.loadtest.com
Las Vegas
O-cells in Barrettes
www.fugro.comwww.loadtest.com
Alfaro’s Peak, Manila, Philippines
O-cells in Barrettes
www.fugro.comwww.loadtest.com
Barrettes - St. Petersburg, Russia
• 60 m deep
• 90 MN capacity
www.fugro.comwww.loadtest.com
O-cells in Driven PilesO-cell cast into or welded
to pile before drivingO-cell grouted into pile
after driving
66” Cylinder Pile, Harrison County, MS30” PSC Pile, Morgan City, LA
www.fugro.comwww.loadtest.com
Example: 18” Steel Pipe Piles, MASaugus River Bridge Pines River Bridge• Delmag
D62-22• Refusal
10 blows per 0.5”
• 142 tons O-cell Load
• 0.28 tsf Side Resistance Failure (0.3”)
• 80 tsfEnd Bearing (not failed)
• 284 tons Capacity
• DelmagD36-13
• Refusal 10 blows per 0.5”
• 215 tons O-cell Load
• 0.39 tsf Side Resistance Failure (0.3”)
• 122 tsfEnd Bearing (not failed)
• 430 tons Capacity
www.fugro.comwww.loadtest.com
FL Research Pile Setup
• Five 18” PSC Piles• PDA Tests• Long-term, staged
static tests (25)• Osterberg Cell in tip• Strain Gages• Telltales• Piezometers• DMT Stress Cells Osterberg Cell
Cast Into Pile,with XXS Pressure Pipe to Top
PileSideShear
Pile End Bearing
O-cell® TopTelltales Inside PVC Pipe
O-cell® Bottom Telltale (through center of pressure pipe)
Friction Collarfor Gage Support O-cell®
Tee
(not to scale)
Dilatometer Cell (L)& VW Piezometer (R)on Pile Face
VW Strain Gage(in pairs, tied to prestress strands)
Hydraulic Pumpwith Gage& Piezometer
Wireline & Scale
www.fugro.comwww.loadtest.com
FL Research Pile Setup: O-cell
www.fugro.comwww.loadtest.com
0 50 100 150 200 250 3000
500
1000
1500
2000
2500
Aucilla, Static TestAucilla, Dynamic Test
1 min
15 min
60 min
1727 days
Elapsed Time, t (days)
Pile
Sid
e Sh
ear
QS
(kN
)
Bullock et al. (1995) in FL18” PSC, O-cell at bottom
FL Research Pile Setup – Arithmetic Plot
= 225 tons
www.fugro.comwww.loadtest.com
0.001 0.01 0.1 1 10 100 10000
500
1000
1500
2000
2500
Aucilla, Static TestAucilla, Dynamic Test
1 min
15 min
60 min
QS0 =1021 kN (at t0 = 1day )
mS = 293.4 kN
Elapsed Time, t (days)
Pile
Sid
e Sh
ear
QS
(kN
)
Bullock et al. (1995) in FL18” PSC, O-cell at bottom
(EOID Capacity plotted at 1 min)
FL Research Pile Setup – Log-linear Plot
= 225 tons
www.fugro.comwww.loadtest.com
where: A = Dimensionless setup factorQS = Side shear capacity at time tQS0 = Side shear capacity at reference time t0fS = Unit side shear capacity at time tfS0 = Unit side shear capacity at reference time t0t = Time elapsed since EOD, dayst0 = Reference time, recommended to use 1 daymS = Semilog-linear slope of QS vs. log t
Note: “A” is correlated to soil type (0.1 to 0.8) anddescribes the capacity increase per log cycle of time (relative to the reference capacity)
1log1log00000
tt
Qm
ttA
ff
S
S
S
S
S
S
Non-dimensional side shear setup:
www.fugro.comwww.loadtest.com
0.001 0.01 0.1 1 10 100 10000.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2Aucilla, Dynamic Test
Aucilla, Static Test
A = (mS / QS0) = 0.30R2 = 0.99
1 min
15 min
60 min
Elapsed Time Ratio, ( t / t0 ) with t0 = 1 day
Pile
Sid
e Sh
ear
Rat
io, (
Qs /
Qs0
)
Bullock et al. (1995) in FL18” PSC, O-cell at bottom
+30%
+30%
+30%
Σ = +90% in 1 day(or 9X 1 min capacity)
1-3d+14 %
1-7d+25%
1-28d +43% orabout half ofEOD-1d change
FL Research Pile – Non-dimensional Plot
www.fugro.comwww.loadtest.com
Example: Morgan City, LA - 30” PSC• HPSI 2500, 300 bpf• 30” PSC, 18” Void, 143 ft long• Pile Setup Clay/Sand• 950 ton O-cell
369 tons at 1wk
416 tons at 3 wks
464 tons at 5 wksMax. O-cell Load 493 tons
Buoyant Pile Weight 29 tons
www.fugro.comwww.loadtest.com
Example: Busan, Korea - 24” PHC• Prestressed Spun High Strength Conc.• 24” OD, 16” ID, 103 ft long, 46 ft sections• Sand / Clay / Sand• 875 ton O-cell, 7 Strain Levels, Grouted
Buoyant Pile Weight 16 tons Max. Side Shear 456 tons
Unit Side Shear 0.14 to 1.98 tsf
Max. O-cell Load 472 tons (944 ton test)
Max. End Bearing 155 tsf
www.fugro.comwww.loadtest.com
Example: Harrison County, MS - 66” Cylinder
• Conmaco 300, 128 bpf EOID• 66” OD, 54” ID, 108 ft long• Silt / Sand / Dense Sand• 3000 ton O-cell, 4 Strain Levels
Buoyant Pile Weight 114 tons Max. Side Shear 626 tons
Unit Side Shear 0.23 to 4.10 tsf
Max. End Bearing 45 tsf
Max. O-cell Load 740 tons (1480 ton test)
www.fugro.comwww.loadtest.com
O-cell Tests World-Wide
1-1011-2021-30>30
0
Upcoming/In progress
Key
www.fugro.comwww.loadtest.com
Carquinez Bridge, Vallejo, CA Benicia-Martinez Bridge
O-cell Application: Bridges
Sheik Zayed Bridge, UAE My Thuan Bridge, Vietnam
www.fugro.comwww.loadtest.com
Cooper River, SC Jiangsu Sutong, China
O-cell Application: Bridges
Confederation, PEI/NB Panama 2nd Bridge
www.fugro.comwww.loadtest.com
O-cell Applications: Buildings
Venetian Hoteland Casino,
Las Vegas, NV
One Raffles Quay,
Singapore
Four Seasons Hotel Miami, FL
www.fugro.comwww.loadtest.com
O-cell Applications: Buildings UAE
23 Marina Tower Al Rafi Towers
Infinity Tower
www.fugro.comwww.loadtest.com
• Test drilled shafts (wet/dry), CFA piles, driven concrete or steel piles, barrettes
• Separates side shear & end bearing• Very high load capability (321MN, St. Louis)• Direct loading of rock socket• Cost, safety, and space advantages• No additional reaction system needed• Doubles effective jack load• Post-test grouting for production piles
O-cell Static Load Test Advantages
www.fugro.comwww.loadtest.com
Efficient O-cell Test Applications
• End bearing side resistance (use ultimate!)• Restricted site access (remote location, existing
structures, environmentally sensitive, water)• Prove capacity distribution (end bearing vs. side
resistance, unit side resistance)• Accelerated construction schedule• Large test loads required• Site safety restrictions (personnel & equipment)• Repeated tests (setup)• Multiple test piles (but only one test frame)• Compare with total cost of conventional testing
www.fugro.comwww.loadtest.com
• Pile preselected for testing• Maximum load limited by the weaker of the
end bearing or side shear (add top load?)• Top of pile not structurally tested • Subtract buoyant weight of pile above O-cell
to calculate side resistance• Must construct equivalent top load
movement curve• use the sum of measured behavior• use the sum of modeled behavior• use finite element or t-z approach
O-cell Test Limitations
www.fugro.comwww.loadtest.com
Typical O-cell Test Result
(1 MN = 112.4 tons)
2,700 tons
www.fugro.comwww.loadtest.com
Equivalent Top-Load Curve
www.fugro.comwww.loadtest.com
Equiv. Top-Load + Elastic Shortening
www.fugro.comwww.loadtest.com
Reduce Cost by Reducing Uncertainty:
• Informed design (integrated investigation: geophysics + insitu testing + sampling)
• Design verification (static & dynamic testing)• Optimization (redesign)
• reduce length, size, number• change type (driven, drilled, anchor)• reduce cost and construction time ($$)• FLT’s experience - savings >5X test cost
• Quality control testing to reduce cost of post-construction remediation
www.fugro.comwww.loadtest.com
25 4445
46
9574
123
94
75
25
109 88
89
40
28 29
127
128
105
104
35
37
31
M/E=25
106
38
Ratio of Measured / Estimated Capacity
128 = LOADTEST Project Reference no.
Schmertmann &Hayes
M/E
1
5
10
15
Soft to Hard Soils Intermediate Hard Rock
One of FLT’s first major discoveries! (How designers handle uncertainty
i.e. lower expectations lead to higher costs)
www.fugro.comwww.loadtest.com
25 4445
46
9574
123
94
75
25
109 88
89
40
28 29
127
128
105
104
35
37
31
M/E=25
106
38
1
5
10
15
Wasted value due to uncertainty and complacency
Ratio of Measured / Estimated Capacity
M/E
Soft to Hard Soils Intermediate Hard Rock
One of FLT’s first major discoveries! (How designers handle uncertainty
i.e. lower expectations lead to higher costs)
www.fugro.comwww.loadtest.com
Initial Design• 9 m Rock Sockets (“typical”)• Design side shear: 1.3 MPa (code)
O-cell Tests• 2 Shafts with 1.5 m rock sockets• Measured side shear: 2.7 MPaEstimated vs. Actual Costs• Final design: 4.5 m rock sockets• Design FS = 3, Measured FS > 5• Redesign FS > 2• Fdn. Cost Est.: $18,000,000• Testing cost: $ 255,000 • Fdn. redesign cost: $ 8,900,000• Net Savings: $ 8,845,000
Cost Savings: Seacaucus NJ Transfer Station
www.fugro.comwww.loadtest.com
Job Number 566 775 835 381 056* 335 426 635
State CA FL NC NJ SC GA TX FL
Fdn. Estimate $850 $6,200 $32,500 $18,000 $160,000 $3,270 $8,500 $4,520
Fdn. Redesign $610 $4,980 $24,500 $8,900 $125,000 $3,003 $8,500 $7,232
Savings $240 $1,220 $8,000 $9,100 $35,000 $273 $0 -$2,712
Test Cost $79 $360 $2,000 $255 $7,500 $240 $95 $305
Net Savings $161 $855 $6,000 $8,845 $27,500 $33 -$95 -$3,017
Calculated FS 2.5 3.0 3.0 3.0 3.0 3.0 3.0 2.5
Measured FS 3.0 3.5 4.0 5.0 NA 3.5 9.5 0.8
Redesign FS 2.0 2.0 2.0 2.0 2.0 2.3 9.5 2.0
Foundation Savings After Testing Based On Actual Jobs Completed (Thousands)
• More than 70% of the FLT testing saved the client money• Half of the remaining 30%, testing done too late to realize the savings• Only a few estimates were so close not to allow a modified foundation
O-cell Tests Result in Project Cost Savings
www.fugro.comwww.loadtest.com
Reduce Cost by Reducing Uncertainty:
• Informed design (integrated investigation: geophysics + insitu testing + sampling)
• Design verification (static & dynamic testing)• Optimization (redesign)
• reduce length, size, number• change type (driven, drilled, anchor)• reduce cost and construction time ($$)• FLT’s experience - savings 5X test cost
• Quality control testing to assure performance & reduce remediation cost
www.fugro.comwww.loadtest.com
Deep Foundation Quality Control• Driven Piles
• Blow Count, Hammer Energy, Dynamic Tests• Drilled Shafts
• Control Slurry Properties• Prepare Excavation Log• Shaft Profile - Sonic Caliper• Clean Shaft Bottom
– MiniSID, Downhole Camera• Concrete Quality - Pile Integrity Test,
Crosshole Sonic Logging, Thermal, Gamma• Verify Pile Capacity using RIM-cell
www.fugro.comwww.loadtest.com
Shaft Profile - SONICALIPER
www.fugro.comwww.loadtest.com
Uses sound reflection360°profile of shaft wallsChecks hole verticality and driftReal-time results6 mm Accuracy, 3-D modelingPortable and compactMinimal impact to schedule
Shaft Profile - SONICALIPER
www.fugro.comwww.loadtest.com
• Verticality• Cage Encroachment• Calculate Concrete
Volume
Shaft Profile Report - SONICALIPER
www.fugro.comwww.loadtest.com
Shaft Volume - SONICALIPER
www.fugro.comwww.loadtest.com
• RIM-cell pressurizes pile cross-section• Full-scale static bi-directional load test• Install a RIM-cell in any pile• Economical testing• QA/QC device eliminates uncertainty• End-bearing engaged during test,
stiffens shaft response under load
RIM-CELL
60” RIM-cell
www.fugro.comwww.loadtest.com
Cross-section of a RIM-cell installed at the shaft toe.
RIM-CELLTESTING
www.fugro.comwww.loadtest.com
The RIM-cell confines the fluid pressure, creating a hydraulic cylinder at the shaft toe capable of applying high static loads.
RIM-CELLTESTING
www.fugro.comwww.loadtest.com
Fluid grout is pumped through the hydraulic hoses creating a fracture across the shaft, pressurized within the RIM-cell.
RIM-CELLTESTING
www.fugro.comwww.loadtest.com
As the internal grout sets, more grout is pumped into external pipes to fill the annular fracture around the RIM-cell.
RIM-CELLTESTING
www.fugro.comwww.loadtest.com
RIM-CELL Applications• PROOF TEST
• Install in every pile• Load shafts to design load or
higher (2000 – 5000 psi)• Eliminate uncertainty of site
variability• Use higher LRFD factors• Detect / remediate a “soft toe”
• POST-STRESSING• Consolidate loose material at
shaft toe• Engage end bearing without
losing side shear• Limit settlement at service load
www.fugro.comwww.loadtest.com
RIM-CELL AssemblyRIM-cell fits inside reinforcing cage. Hydraulic hoses and instrumentation
pipe installed on cage. Add strain gages to isolate different soil strata.
RIM-cell welded to frame below O-cell assembly for a
multi-level test shaft.
24” RIM-cell installed with 8 levels of strain gages
60” RIM-cell
www.fugro.comwww.loadtest.com
Excavate shaft and place cage with RIM-cell. Large center opening allows tremie pipe to pass. Low
cross-sectional area does not inhibit concrete flow or trap weak material.
RIM-CELL Installation
60” RIM-cell installed into 78” rock socket
24” RIM-cell at toe of an O-cell test shaft
20” RIM-cell installed at the toe of 30” shaft
www.fugro.comwww.loadtest.com
Perform test after concrete obtains strength. Cement grout is mixed and pumped through the hydraulic hoses into the RIM-cell. Measured pressure is converted to load using calibration factor of the RIM-cell. Load is increased to 1.2 to 1.5 times design load. Shaft movement is measured and recorded. Grout will set up to restore integrity to the shaft.
24” RIM-cell Test Curve 36” RIM-cell Test Curve
RIM-CELL Testing
www.fugro.comwww.loadtest.com
Similar to O-cell with real-time Load-Displacement plot during
test. Preliminary results available same day as test.
RIM-CELL Reporting
60” RIM-cell
Schematic section of RIM-cell
shaft
Equivalent Top Load Plot
www.fugro.comwww.loadtest.com
RIM-CELL Limitations
• Internal friction unknown (but small)• Preselect shaft
(install in every shaft, test as required)• Reduced pressure vs. O-cell
(but large area)• Typically will not test to failure• Grouting required to restore shaft integrity• Maximum load limited by the weaker of the
end bearing or side shear (add top load?)• Top of pile not structurally tested
www.fugro.comwww.loadtest.com
Missouri Research Project
• 24” bi-directional test piles on two different sites
• Two piles on each site were tested using RIM-cells
• 24” RIM-cells in 36” piles• 20-30 feet deep shafts in
unweathered and weathered shale
• Side by side comparison to O-cell tests
24” (600mm) RIM-CELL Tests
www.fugro.comwww.loadtest.com
24” RIM-CELL Tests
Similar piles on same site. O-cell test (red) mobilizes ultimate capacity. RIM-cell test (blue) confirms design load.
www.fugro.comwww.loadtest.com
RIM-CELL Tests to DateRIM‐cell Size Shaft Diameter Max
PressureMax Cell Load Test Result
14" 24" 2500 psi 350 kips Side Shear Failure
14" 24" 1780 psi 250 kips End Bearing Failure
20" 30" 1530 psi 450 kips Side Shear Failure
20" 30" 1360 psi 400 kips Side Shear Failure
24" 36" 2560 psi 1100 kips RIM‐cell Capacity Maxed Out
24" 36" 1980 psi 850 kips RIM‐cell Capacity Maxed Out
24" 36" 640 psi 275 kips End Bearing Failure
24" 36" 1170 psi 500 kips End Bearing Failure
24" 30" 940 psi 400 kips Test stopped at 1" Expansion
36" 54" 475 psi 450 kips Side Shear Failure
60"96"
(76"rock socket) 4950 psi 13,000 kips Test stopped at 1/2" Expansion
www.fugro.comwww.loadtest.com
Summary• O-cell test proven for shafts and driven piles• Compare overall cost and quality of test
results for conventional top-down testing with O-cell testing
• RIM-CELL tests to verify production pile capacity (QA/QC)
• Coming Attractions:• New ASTM Standard• Bigger piles, higher loads• Mid-pile O-cell placement for spliced
concrete piles• Mid-pile placement for steel pipe piles
www.fugro.comwww.loadtest.com
Summary
• Deep foundation design generally conservative due to uncertainty.
• Correlate site characterization with foundation design and testing. Reduce project cost through more efficient design and construction. Reduce uncertainty.
• Use a portion of the cost savings to fund the testing and inspection needed for more efficient design.
“The owner pays for a good site investigation whether he does one or not.”
www.fugro.comwww.loadtest.com
Thank You
www.loadtest.comwww.fugro.com