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UW GIGSS Presentation 2011.02.23
- 1. SR 532 Widening Project Stillaguamish River Bridge Replacement Mike Harney, MS, PE Oliver Hoopes, MS, EIT Stan Boyle, PhD, PE Shannon & Wilson February 23, 2011
- 2. Outline • Design-Build • SR 532 Widening Project • Stillaguamish River Bridge – Subsurface Conditions – Geotechnical Design – Geotechnical Construction • Summary
- 3. Traditional Design-Bid-Build Identify Owner Project Design Plans and Specifications Team Bid Contractor Construct
- 4. Design-Build Owner Identify Project Preliminary Concept Plans RFP / Bid Contractor D-B Team Design Designer Construct
- 5. Why do D-B? Schedule! – SR 532 Typical Project Delivery 36 - 48 Months Design Bid Build Design Build Delivery RFP 25 Months Example: SR 532 Bid •Cut ~1 to 2 years off Design schedule Build •$25 million (35%) under budget Risk
- 6. Design Build Examples Tacoma Narrows Third Bridge, Tacoma, WA Port Mann Bridge Replacement, Surrey, BC
- 7. Design Build Examples I-405 Tukwila to Everett, WA Cleveland Innerbelt I-90
- 8. SR 532 Widening Project • Increase safety • Reduce congestion • Maintain infrastructure • A better environment • Remove and replace existing 2-lane bridge • New 56-ft-wide bridge: 2 traffic lanes, 2 14-ft shoulders, 4-ft median • Improve horizontal and vertical curvature • Reduce west approach/abutment footprint for wetland mitigation
- 9. SR 532 Widening Project Stillaguamish River Bridge Climbing Lanes New bridge Climbing lanes Turning lanes Sidewalks
- 10. WSDOT RFP Concept Bridge Retaining Walls Ground Improvement Bridge Piers
- 11. DBT Concept Bridge – As-Built Ground Improvement Bridge Piers Retaining Walls Unreinforced Slopes Reinforced Slopes • Eliminated Walls • Converted Walls to Less-Costly Slopes • Eliminated Ground Improvement • Removed Bridge Pier from the River
- 12. Existing Subsurface Information Data Gap? Data Gap? 130 ft bgs Deep enough? from Project RFP, Appendix G1 (GeoEngineers, 2008) Fines content? Interbedded or homogeneous? Plasticity?
- 14. Geotechnical Design: Stillaguamish River Bridge • Liquefaction Susceptibility • Soil Parameters – Liquefied Condition – Static Condition • Approach Embankments/Abutment Walls – Global Stability (East Abutment STA 193) – Bearing/Sliding Resistance – Lateral Earth Pressures • Seismic-Induced Lateral Spreading • Drilled Shaft Foundations • Seismic Design Parameters
- 15. Generalized Subsurface Profile: Stillaguamish River Bridge UPPER SILT SAND LOWER SILT SAND & GRAVEL Deepest Exploration ~200 feet
- 16. Generalized Subsurface Profile: Stillaguamish River Bridge UPPER SILT SAND LOWER SILT SAND & GRAVEL Deepest Exploration ~200 feet
- 17. UPPER SILT SAND LOWER SILT SAND & GRAVEL
- 18. Effective Stress Seismic Site Response: Estimated Porewater Pressure Ratios, Ru Ru = u/’vo UPPER SILT Residual Strength SAND USED Ru = 0.2 Reduced Strength w/ LOWER SILT Ru = 0.2 No Progressive Liquefaction PSNL DMOD2000 (CH2MHill DSS tests indicate (Kramer, 2009) (CH2MHill, 2009) dilative behavior)
- 19. Generalized Subsurface Profile: Stillaguamish River Bridge UPPER SILT Residual SAND Strength LOWER SILT Strength Reduced SAND & GRAVEL Static Strength
- 20. Post-Seismic Strength: (psf) UPPER SILT SLIGHTLY SILTY SAND 70’ – 80’: used Ru = 0.2, Reduced ’ = 23° LOWER SILT
- 21. Upper Silt: Consolidated-Undrained Triaxial Testing (used 32°)
- 22. Lenz Pit “Blend” Consolidated-Undrained Triaxial Testing (Series Resulted in Effective Friction Angle of 40°)
- 23. Embankment Global Stability STA 193+00 ANALYSIS Liquefaction Susceptible Soil
- 24. Static Global Stability – No Stone Columns FS < 1.5 N.G. Upper sandy SILT Fine SAND interbedded with SILT seams Lower clayey SILT Med. Dense to Dense Silty Fine SAND and Fine Sandy SILT Med. Dense to Dense Sandy GRAVEL Dense to Very Dense, Gravelly SAND
- 25. Post-Seismic Global Stability – No Stone Columns FS << 1.1 N.G.! Upper sandy SILT Fine SAND interbedded with SILT seams Lower clayey SILT Med. Dense to Dense Silty Fine SAND and Fine Sandy SILT Med. Dense to Dense Sandy GRAVEL Dense to Very Dense, Gravelly SAND
- 26. Post-Seismic Global Stability – With Stone Columns FS > 1.1 O.K.! Stone Columns in SILT Upper SILT Stone Columns in SAND Fine SAND interbedded with SILT seams Lower clayey SILT Med. Dense to Dense Silty Fine SAND and Fine Sandy SILT Med. Dense to Dense Sandy GRAVEL Dense to Very Dense, Gravelly SAND
- 27. Static Global Stability – With Stone Columns FS > 1.5 O.K.! Stone Columns in SILT Upper SILT Stone Columns in SAND Fine SAND interbedded with SILT seams Lower clayey SILT Med. Dense to Dense Silty Fine SAND and Fine Sandy SILT Med. Dense to Dense Sandy GRAVEL Dense to Very Dense, Gravelly SAND
- 31. Stone Column Ground Improvement Stone Columns Sheet Pile Shoring Existing SR 532 Roadway and Bridge Piers
- 32. Stone Column Ground Improvement Purpose • Mitigate liquefaction-induced instability of abutments – within 100-ft of bridge (thicker cohesionless deposits) • Achieve target static FS of MSE walls (surficial silt)
- 33. Stone Column Ground Improvement Surficial Silt Liquefaction Susceptible Soil
- 34. Stone Column Ground Improvement Secondary Columns Primary Columns
- 35. Stone Column Ground Improvement Dual Specification • DENSIFICATION in cohesionless, liquefaction-susceptible deposits: Performance-based spec • REPLACEMENT in shallow silt deposit: Prescriptive spec
- 36. Stone Column Ground Improvement Performance Specification Densification Target CPT-Equivalent SPT N60
- 37. Stone Column Ground Improvement “Unit” Cell Prescriptive Specification Required Composite Ф’ = 40° Secondary Silt: Ф’ = 34° 8 ft Column Dia. = 45” Aggregate: Ф’ = 50° Area Replacement Ratio = 37% Primary Column Diameter = 48”
- 38. Stone Column Ground Improvement Primary Columns – Liquefaction Mitigation Secondary Columns – Replace Silt
- 39. Stone Column Ground Improvement Dry Bottom-Feed Method Hopper Tremie Tube Tremie Probe Vibro-Probe Skip Bucket
- 40. Stone Column Ground Improvement Probe is vibrated as stone flows through the tremie to densify loose soil and work stone into ground.
- 41. Stone Column Ground Improvement
- 42. A messy business
- 43. A messy business
- 44. Stone Column Ground Improvement Containment berm
- 45. Elevated Pore Water Pressures?
- 46. Stone Column Ground Improvement Sand boils
- 47. Stone Column Ground Improvement Air migration
- 50. Approach MSE Walls and RSS
- 51. Approach MSE Walls and RSS
- 52. Approach MSE Walls and RSS
- 53. Approach MSE Walls and RSS
- 54. Approach MSE Walls and RSS
- 55. Approach MSE Walls and RSS
- 56. Approach MSE Walls and RSS
- 57. Approach MSE Walls and RSS
- 58. Summary • Design-Build Project Delivery • Creative, Innovative Engineering • Opportunity to work with Contractor • Application of Concepts from Curriculum • Site characterization and lab testing • Geotechnical earthquake engineering • Stability analyses, walls, ground improvement • Successful Project!
- 59. Questions