Cylinder Pile Production. Spinning, Post tensioning. Steel Pile Properties. Topics. Large Diameter Open Ended Pipe Piles. Moving and Installing

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1 Large Diameter Open Ended Pipe Piles Cylinder Pile Production Frank Rausche, GRL Engineers Day, Pile Dynamics, Inc. 4 LDOEP, PDCA Professors Course, 215 Topics Pile Properties Cylinder and pipe pile details Damage potential The FHWA Synthesis Cylinder pile topics Plug formation, a study Very large pile example Summary Spinning, Post tensioning Photos: courtesy Don Theobald, Gulf Coast Prestress 2 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Steel Pile Properties Rolled pipe diameters unlimited; spiral welded 1 Wall thickness 1 max for spiral weld Moving and Installing 3 LDOEP, PDCA Professors Course, 215 1

2 Cylinder Pile Properties Sizes: US: 36x5, 54x5, 66x6 (91x13, 137x13/15, 168x15 mm) Other countries: 16, 2, 3 (4, 5, 75 mm) Concrete strengths: US: 6 to 8 ksi (42 55 MPa) Other countries: same or more Static Bending Stresses W H W p Jacket Leg 7 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Driving systems Driving systems Leads which do not sway, bend piles Hammer cushion: man made material, uniformly worn Helmet: well fitting, evenly striking surface; skirt not to apply horizontal forces Pile cushion: plywood stacks, engineered and well assembled 8 LDOEP, PDCA Professors Course, 215 Driving systems Pile Stabbing Add On Stabbing Guide Temp. Pile Top 9 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 2

3 A well designed driving system prevents bending stresses, eccentricities Pile top forces Non-uniformly worn cushion Eccentric, misaligned driving forces Poorly fitting helmet Cushion expansion force Strand anchoring forces Helmet lateral force Concrete quality problems Photograph: Courtesy Massman Construction Grout pressure 16 LDOEP, PDCA Professors Course, 215 Problems Vertical Cracking Top Damage Non-uniformly worn cushion Pile top forces Non-uniform Internal guide problems cushion force Ouch Internal helmet lateral force 14 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Pile top damage due to: Uniform driving stresses plus prestress Hammer eccentricity and misalignment Limited effectiveness of hoop reinforcement Complex stress state at pile top Tensile stress pile damage Low ram/pile weight ratios cause for high tension stresses both when driving is easy and when it is very hard Additional bending stresses particularly in battered pile driving High tension/compression stress cycles cause small tension cracks and eventually damage, particularly under water 15 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 3

4 Recommendations for damage prevention Reduction of allowable driving stresses from 85% to 66% of strength minus prestress Monitoring of driving stresses Well engineered driving system Well aligned hammer pile to prevent bending Careful grouting and prestressing High quality concrete and curing Some relevant statements Large diameter open ended piles (LDOEPs) are steel or prestressed concrete cylinders 36 or larger in diameter which can provide large axial and lateral resistance even in relatively poor soil conditions Load and Resistance Factor Design (LRFD) methods for piles were calibrated using piles with a diameter of 24 or less Recent or current projects with LDOEPs San Francisco Oakland Bay Bridge, Woodrow Wilson Bridge, Tappan Zee Bridge, Kentucky Lakes Bridge,.. in New York which is currently under construction 19 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Bending / Local Stress concentrations due to Hammer Weight Pile Batter Barge/crane/lead motion add to Driving and pre stress, post tensioning stresses also Non uniform soil resistance adds to unpredictable additional stresses Ouch 2 LDOEP, PDCA Professors Course, 215 Synthesis Results 23 LDOEP, PDCA Professors Course, 215 The Synthesis Synthesis Results 21 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 4

5 Synthesis Results Synthesis Results 25 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Synthesis Results Synthesis results McVay dia OE Cylinder pile Determined critical g level of 15 g s for plug slipping Static: 1962 kips R total CAPWAP restrike with set and no superposition: 1266 kips (Note: Superpostion uses end bearing from EOD and Shaft resistance from BOR) 26 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Synthesis Results Synthesis results Alaska DOT 12 to 48 dia piles Developed a design method based on CAPWAP results. The proposed relationships were used to predict pile resistance on a project with 29 monitored piles driven into silt-rich deltaic deposits. Dickenson reported Overall, the agreement between the predictions and the CAPWAP results was good to excellent, and the proposed method provided much more reliable ranges of estimated pile resistance than obtained using widely-adopted, standard of practice procedures. 27 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 5

6 Synthesis results Synthesis results: Kentucky Lakes A Comparison of Dynamic and Static Pile Test Results (OTC, Stevens 213): 48 dia OEPipe Piles at 4 and 65 depth Uplift Static: 118 and 253 kips R shaft CAPWAP: 129 and 253 kips 78 dia OEPipe Piles at 11 Uplift Static: 5875 kips R shaft CAPWAP: 593 kips (extrapolated to 53 days using pore water pressure measurements) 31 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Synthesis results Kentucky Lakes, Terracon 48 and 72 dia OEpipe piles with 1 to 2 wall thickness 48 plug models after Paikowsky Synthesis results: Kentucky Lakes For the dynamic records where radiation damping was applied, the model generally resulted in a significantly better signal match quality, indicating the radiation damping allows CAPWAP to better model the signals recorded by the dynamic pile testing equipment. The pile resistances calculated with CAPWAP using the radiation damping model also generally produced higher end bearing resistance values than the CAPWAP models without the radiation damping. It appears that the radiation damping model is better suited for estimating the end bearing component of the piles when less pile set is experienced per hammer blow. This is the case when the constrictor plates are engaged on the dense granular soils. Wave equation analyses indicated that plugged piles would have high stresses. Additionally there was concern that localized high stresses might be encountered due to the presence of the chert. Testing on the piles typically did not approach as high values as expected. 32 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Synthesis results Kentucky Lakes, Terracon US 378 Bridge over Pee Dee River (South Carolina) S&ME Two 54 dia cylinder piles Synthesis results To monitor the formation of a plug in the interior of the pile, a simple device called a pile plug monitoring device (PPMD) was constructed. The PPMD consisted of lead weights attached to a 1 foot fiberglass measuring tape. The weights would fall to the top of the soil column inside of the piles, allowing the distance to the soil to be computed. Access to the interior of the pile was made through a vent hole near the top of the pile. The PPMDs were read intermittently throughout test pile installation. The data showed that soil was rising inside both piles during driving, indicating that disturbed soil and water was accumulating in the pile rather than a pile plug forming and traveling down with the pile. 33 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 6

7 Synthesis results US 378 Bridge over Pee Dee River (South Carolina) S&ME!! Inertia force Dynamic Plugging? Soil column Pile wall Internal friction on pipe End Bearing Internal Friction on plug 37 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Longitudinal cracks Potential causes: Poisson s effect and/or insufficient hoop reinforcement (may not be a problem) complex stress state at pile top or pile bottom concrete and/or manufacturing defects internal hydrostatic water pressure (provide water escape hole) internal excess soil or pore water pressure (wash out plug, bail out water!) internal dynamic air/water pressure CANNOT BE DETECTED BY PDA Dynamic Considerations: Plug inertia vs internal resistance 5 Assuming a plug length equal to 1, 3 and 5 diameter 4 pile diameters 3 Assuming 1 g s steel acceleration 2 The graph shows internal 1 friction and inertia (no end bearing) Inertia or Internal Resistance (kips) 1D Plug Inertia 3D Plug Inertia 5D Plug Inertia 1D Plug Ri 3D Plug Ri 5D Plug Ri Diameter (Inches) Conclusion: under these VERY simplified circumstances a plug will slip if the diameter is more than ~4 inches 38 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Static Plugging Unplugged pile toe acceleration Concrete cylinder pile Internal soil column Pile wall Internal friction on pipe Toe Acceleration (g's) Hydraulic 8" Cushion Hydraulic 12" Cushion Hydraulic 15" Cushion Diesel 8" Cushion Diesel 12" Cushion Diesel 15" Cushion End Bearing 39 LDOEP, PDCA Professors Course, 215 Internal Friction (from arching?) on plug 4 3 4% 5% 6% 7% 8% 9% Analyzed Stroke Relative to Rated Stroke Figure 3: Relative Toe Acceleration for Unplugged Cylinder Piles 42 LDOEP, PDCA Professors Course, 215 7

8 Soil inertia and toe resistance on plug Inertia Force Toe Resistance on Plug Total Loss of friction due to pile lateral motions 4 Force (kn) L p f s f s -4 F i Pile Time (ms) q toe q u 43 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Loss of Resistance Due to Pile Driving Loss of friction due to arching Sand porewater pressure changes Liquefaction Clay remolding, thixotrophy Other? Arching in granular soils not during driving at toe: reduced end bearing During driving at shaft: reduced friction Pile Soil-pile interface with reduced effective stresses Compressed, higher density soil 44 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Loss of friction due to pile lateral motions Pile Friction Fatigue: Loss of resistance Friction fatigue considers that the SRD is equal to the LTSR at the pile toe and decreases exponentially above the toe (loss depends on the distance from the toe) R residual (SRD) R initial (LTSR) Depth below mudline in m Resistance per1 m segment in kn LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 8

9 Friction Fatigue: Loss of resistance R residual (SRD) R initial (LTSR) Depth below mudline in m Resistance per1 m segment in kn GRLWEAP Friction Fatigue Approach Resistance Ratio, f s (say 5?) f s = R initial /R residual Degradation distance, L l (Limit Length, 2 to 15 m) Undegraded distance, f L say.5) Exponent for degradation shape, f o (say.1) R residual (SRD) R initial (LTSR) Distance from Bottom Example: fs=5, L l =5, fo=.1; fl= Long Term Capacity Multiplier L l f L See Alm and Hamre, 21. Soil model for pile driveability based on CPT interpretation. Proc. 15 th Int Conf. on Soil Mechanics and Geotechnical Engineering, Istanbul 66 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Friction Fatigue: Loss of resistance R residual (SRD) R initial (LTSR) Depth below mudline in m Resistance per1 m segment in kn Steel External and Internal Pipe Friction, f sti, q sti,f ste, q ste Plug Wt Plug modeling Plug Plug Inertia In Preparation of an improved GRLWEAP/CAPWAP model let us consider what we must calculate: Displacement of steel and plug Velocity of steel and plug Unknowns to be determined: f ste, q ste f sti, q sti r st, q st r pl, q p plus damping r t,st q t r P, q p,t 67 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, 215 Friction Fatigue: Loss of resistance Friction fatigue considers that the SRD is equal to the LTSR at the pile toe and decreases exponentially above the toe (loss depends on the distance from the toe) In contrast, the standard GRLWEAP approach assumes full loss of resistance in a particular soil layer. Depth below mudline in m Resistance per1 m segment in kn m depth 5 m depth 75 m Depth 68 LDOEP, PDCA Professors Course, 215 Simplified model: single plug mass Unknowns to be determined: f ste, q ste, f sti, q sti, r pl, q p plus damping Plug Wit Full End Bearing Pipe Pile Steel only Acceleration from GW - easy driving Diameter inch D 18 Wall thickness inch t.5 Area in^2 A Pile segment length inch dl 4 Soil plug length inch dpl 72. Segment weight above toe segment k w1.313 mass above last pile segment k/f/s2 m1.1 weight of last pile segment k w2.313 mass of last pile segment k/f/s2 m2.1 weight of plug k wp.945 mass of plug k/f/s2 mp.2 internal limit friction F-int. ksf 5. internal limit friction F-int. kips unit res against steel ru-toe-s ksf 25. unit res against steel rutoe-s ksi Steel toe resistance ult Rutoe-s k unit res against plug ru-toe-p ksf 125. unit res against plug rutoe-p ksi.868 Soil toe resistance Rutoe-p k q steel toe qs inch.1 q soil plug qp inch.283 Rel. plug length Lplug diameters 4. q internal friction qfi inch.1 Note, this model uses unloading =loading quake as per GRLWEAP 71 LDOEP, PDCA Professors Course, 215 9

10 -5 2 Vel in inch/s -2 Displ. in inches Example 18 inch pile INPUT - Easy driving record Acceleration in g's a steel a steel ms force - kips Pile is rigidly linked to plug displacements are the same. Easy driving record Plug rigidly linked to steel R steel Rplug-no slip Rtotal-no slip Acceleration in g's inch/s inches Example 18 inch pile INPUT - Hard driving record a steel a plug ms v plug ms d plug force - kips Plug is linked to steel pipe with an elasto plastic spring (R int, q int) time - ms R steel F-int Rplug Inertia Acceleration in g's Vel in inch/s Displ. in inches Example 18 inch pile INPUT - Easy driving record a steel a plug ms v plug d plug Plug is linked to steel pipe with an elasto plastic spring (R int, q int) force - kips All forces time - ms R steel F-int Rplug Inertia Acceleration in g's inch/s inches Example 18 inch pile INPUT - Hard driving record a steel a plug ms v plug ms d plug force - kips Plug is linked to steel pipe with an elasto plastic spring (R int, q int) time - ms R steel F-int Rplug F-pile Rs+Rp 1 Acceleration in g's inch/s inches a steel a steel ms 3 8 ms Example 18 inch pile INPUT - Hard driving record force - kips Pile is rigidly linked to plug displacements are the same. Rigidly linked plug R steel Rplug-no slip Rtotal-no slip Conclusion from simplified plug model The study clearly shows that the full activation of the toe resistance against the plug is as important as plug slippage when attempting to mobilize and calculate full resistance The model has to consider the internal friction on plug and pile the plug compressibility and mass different quakes and unit resistance values for annulus when not plugging and unit toe resistance for plugged analysis 77 LDOEP, PDCA Professors Course, 215 1

11 A Word about Very Large Pipes and Vibratory Analysis 21m dia Steel; APE Octagon; Photo Galerie GRLWEAP Calculated of Rate of Penetration Yangtze Caisson Penetration Speed - mm/s Depth in m % Shaft Res: 3 s 1% Shaft Res: 66 s 78 LDOEP, PDCA Professors Course, LDOEP, PDCA Professors Course, APE 6B 12x.25 m dia concrete shell Thank You Discussion? 79 LDOEP, PDCA Professors Course, 215 GRLWEAP Calculated of Rate of Penetration Yangtze Caisson: 12x.25 m concrete pipe, 25 m long 4 APE 4B hammers (683 kg m, 2 Hz, 3 kw); 8 clamps + beams Clay, silty Sand; N at most 3 Shaft resistance (inside and out) 1 kpa Analyzed at 8% and 1% Toe resistance 9 kpa 8 LDOEP, PDCA Professors Course,