LA Transportation Conference: 10 Jan 2011 Drilled Shaft Foundations For Two Mississippi River Bridges in Louisiana Dan Brown and Associates Projects John James Audubon Bridge, St. Francisville New Construction Design-Build Huey P. Long Bridge, New Orleans New Pier for Widening (existing caissons) Traditional Design-Bid-Build Value Engineered Shaft Construction Method 1
LA Transportation Conference: 10 Jan 2011 Common Features Large: 8 to 9 foot Diameter by 200 feet Deep Fully cased shaft excavations Using either an Oscillator or Rotator Sectional Casing Base grouted Cased-Ahead Construction casing slurry (or water) Do not allow Under-pressure concrete concrete tremie concrete 2
LA Transportation Conference: 10 Jan 2011 The Base Grouting Process 1. Shaft Constructed 2. Base Grout Pressure Applied 3. Some Relaxation Occurs 4. Structural Load Applied Base Grouting Enhance Axial Resistance Improve Reliability Mitigate Imperfections in Base Conditions Criteria: Target Pressure Minimum i Net Volume Limit Upward Shaft Movement 3
LA Transportation Conference: 10 Jan 2011 Scuff Ring Base Grouting Cover Plate Tube á Manchette (using CSL tubes) Audubon Bridge Cable-stayed bridge, 1583 main span Two pylons: 3 x 7 group of 7.5 dia. Shafts High approach: 2 column piers P.E. 4
LA Transportation Conference: 10 Jan 2011 Soil Conditions at Pylons SPT "N" (blows/ft) 0 10 20 30 40 50 60 70 80 90 100 0-50 Silty Sands 0-50 Elevation (ft) -100-150 -200 Sand Sand with Layers of Sandy G l ShftTi Shaft Tip Elevation -100-150 -200 Clay Soils -250-250 -300-300 0 1 2 3 4 5Steven 6 Dapp, 7 Ph.D., 8 P.E. 9 10 Undrained Shear Strength (tsf) Vibro-Drive Permanent Casing LA Transportation Conference LA Transportation 2011 Conference 2011 5
LA Transportation Conference: 10 Jan 2011 Temporary Casing & Oscillator System Excavation Grabs Air-Lift With Jet Ring 6
LA Transportation Conference: 10 Jan 2011 Placement of Reinforcement Base Grouting Steven Dapp, Steven Ph.D., Dapp, P.E. Ph.D., P.E. LA Transportation LA Transportation Conference Conference 2011 2011 7
LA Transportation Conference: 10 Jan 2011 Coffer Cell 1000 900 Base Grouting Measurements Pressure (Auto) Pressure (Manual) Volume 1 8 2 4-3 6-1 5-2 7-8 100 90 800 7 3 80 Grout Pressure (psi) 700 600 500 400 300 6 5 4 Net Net Net 70 60 50 40 30 Grout Volume (cu. ft.) 200 100 Net 20 10 0 0 10 20 30 40 50 Time (minutes) 0 8
LA Transportation Conference: 10 Jan 2011 Shaft Performance During Grouting O-cell Load Testing w/ Reaction Frame Steven Dapp, Steven Ph.D., Dapp, P.E. Ph.D., P.E. LA Transportation LA Transportation Conference Conference 2011 9
LA Transportation Conference: 10 Jan 2011 0 Load Test Results 0 10 O-cell load (MN) 20 136ksf 30 (950psi) 0 Displacement (inches) -1-2 -3-4 -5 Not Grouted Base Grouted -25-51 -76-102 -127 Displacement (mm) -6-152 -7 0 1,000 2,000 3,000 O-cell load (tons) -178 P.E. 0 Load Test Results 0 10 O-cell load (MN) 20 136ksf 30 (950psi) 0 Displacement (inches) -1-2 -3-4 -5-6 -7 Not Grouted 1W Construction Difficulty 4W CISS 0 1,000 2,000 3,000 O-cell load (tons) Base Grouted -25-51 -76-102 -127-152 -178 Displacement (mm) P.E. 10
LA Transportation Conference: 10 Jan 2011 Huey P. Long Bridge Widening Owner: La. DOTD Structural Engineers: Modjeski and Masters Geotechnical Engineers: Eustis Engineering General Contractor: Kiewit/Massman/Traylor Subcontractor: t Malcolm Drilling Company Foundation Consultant: Dan Brown and Associates Existing bridge Pier IVA Pier IVA footing Geo-grid Test reinforced Shaft granular fill Elev (ft) +14 + 0-30 fill Soft silt & clay Willow mat Loose to dense silty sand Production Shafts -140-170 -195 Stiff clay Dense silty sand 11
LA Transportation Conference: 10 Jan 2011 Rotator and Sectional Casing Excavation Using Hammer-grab 24 12
LA Transportation Conference: 10 Jan 2011 Shaft Cleaning & Inspection Airlift SID Bottle Brush Hydraulic Cleaning Bucket (Not Used) Place Gravel 25 Reinforcement Backbone Frame Bar Splices 13
LA Transportation Conference: 10 Jan 2011 Placement of Reinforcement Shaft/Cap Connection Isolation Casing Shaft Cutoff at -11 14
LA Transportation Conference: 10 Jan 2011 Concrete 29 Base Grouting 15
LA Transportation Conference: 10 Jan 2011 Base Grouting QC/QA 31 Cofferdam Shaft Texture 16
LA Transportation Conference: 10 Jan 2011 Performance of Load Test 1.0 0, inches Displacement, 0.8 0.6 0.4 0.2, inches Displacement, 1 2 3 4 5 131ksf 0.0 0 2000 4000 6000 8000 10000 Load, kips 6 0 2000 4000 6000 8000 10000 Load, kips Foundations for large bridges present special challenges: Construction plan to minimize risks Constructability issues of design Coordinated effort of partners Performance verification requirements Summary 17
LA Transportation Conference: 10 Jan 2011 Thank You Louisiana! P.E. 18