Aggregate Pier Ground Improvement for Transportation Projects 2019 - PowerPoint PPT Presentation

Aggregate Pier Ground Improvement for Transportation Projects 2019 Midwest Geotechnical Conference W. Lyle Simonton, P.E. www.subsurfaceconstructors.com

OVERVIEW  Intro to Vibro Ground Improvement  Objectives of Aggregate Pier/Stone Column Ground Improvement  Examples of Transportation Projects (MO, IL, IN, OH, WI, OK, KS, soon to be CT)  Specific Lessons Learned with Ground Improvement Specifications/Install/Testing www.subsurfaceconstructors.com

Vibro-Flot, Probe Hydraulic Motor or www.subsurfaceconstructors.com

Stratocaster Vibro Rigs • 40,000 lbs. of Crowd Force • 90,000 lb. Rig • 1st of these type of rigs in the USA www.subsurfaceconstructors.com

Excavator-Mount Mast System www.subsurfaceconstructors.com

Crane-Suspended Vibro www.subsurfaceconstructors.com

Basic Installation Techniques  Dry Top Feed • Stable, Cohesive Soils • Pre-Drill or No Pre-Drill (hole diam., obstructions)  Dry Bottom Feed • Collapsible Conditions • Stone Tremied to Bottom  Wet Top Feed • Sand / Silty Sand Below WT • Liquefaction Mitigation (with stone) www.subsurfaceconstructors.com

Dry Top Feed Stone Columns (stable soil) www.subsurfaceconstructors.com

Dry Bottom Feed Stone Columns (collapsible soil) www.subsurfaceconstructors.com

Dry Bottom Feed Stone Columns I-69 Indiana Gohmann (GC) SR64 Over I-69 ILDOT Cedar Lake Rd www.subsurfaceconstructors.com E.S Wagner (GC) Round Springs, IL

Wet Top Feed Stone Columns (sand with fines) www.subsurfaceconstructors.com

www.subsurfaceconstructors.com

www.subsurfaceconstructors.com

DOT Projects www.subsurfaceconstructors.com

Objectives of Ground Improvement  MSE Wall and Earth Embankment Support  Bearing Pressure – Range based on wall height (5ksf typ)  Settlement Criteria • Soil parameters critical (CPT preferred) • MSE wall supplier input • Define when/how it’s measured • May need to stage construction  Liquefaction Mitigation • Understand limitations of GI techniques • Cannot substantially densify soils with fines >10% www.subsurfaceconstructors.com

Objectives of Vibro Ground Improvement  Reinforce Soft to Med. Stiff, Cohesive/Fine-Grained Soils • Bearing pressure • Settlement • Not improving the soil strength • Modulus test / monitor settlement  Densify Granular Soils • Bearing pressure • Settlement • Liquefaction mitigation • Substantial improvement proved with SPT/CPT www.subsurfaceconstructors.com 

Design Considerations  Primarily Bearing Pressure and Settlement  Global Stability  Liquefaction Mitigation  Who Does the Design?  Verification Program www.subsurfaceconstructors.com

Specification / Special Provision  Missouri DOT – Aggregate Column Ground Improvement  Experience – Work and Site Superintendent  Aggregate Columns • Vibratory Compacted • Tamper Compacted  Verification Program  Plans indicate bearing pressure, settlement, global stability, etc. www.subsurfaceconstructors.com

Verification Program www.subsurfaceconstructors.com

New I-69 Design Build Indiana DOT  New Interstate From Indianapolis to Evansville  Current Design Build Work - 4 Sections • Section 1 – 13 miles – 5 Contracts • Section 2 – 29 miles – 7 Contracts • Section 3- 25 miles – 7 Contracts • Section 4 – 27 miles – 2 Contracts to Date  Subsurface Constructors Work • Work on 4 - 5 Contracts (with 4 GCs) • Vibro Stone Columns • Wick Drains www.subsurfaceconstructors.com

Design-Build Project Approach  State’s Geotechnical Engineer Makes General Recommendations  Design-Build Team Develops Concepts • Exclusive Agreement with Specialty Contractor • Confidential Agreement with Specialty Contractor, But Not Exclusive  Winning Team Develops Design • May Take Additional Geotech Info • Original Assumptions May Change • Put Ground Improvement Portion Out For Bid To Specialty Contractors www.subsurfaceconstructors.com

Section 3, Segments 12,13  Fred Weber / Jacobs Engineering  I-69 Over CR900E • New Approach/Bridge Over Road • Significant Fill Height of Approach • Approach Embankment (Wick Drains)  Twin Bridges Over Weaver/Vertrees Ditches • No New Embankment / MSE Walls • Bridge Abutment at Grade / Pile Foundations • Liquefaction-Induced Settlement www.subsurfaceconstructors.com

Twin Bridges Over Weaver/Vertrees Ditches  Loose Sands, Sandy Loam To 10 ft to 18 ft  Existing SPT N = 0 to 4  Original Proposal Was Deep Dynamic Compaction  Additional Borings Taken, Team Decided on VSC  Required Post-Treatment SPT N = 8 • Minimize Earthquake Induced Settlement • Designed VSCs = 30” diam, 15ft, 7ft spacing • Diff. Settlement in Transition Zone (further spacing) • Required 9-ft Spacing in Transition Zone www.subsurfaceconstructors.com

www.subsurfaceconstructors.com

BENT 2 Plans Sheets 2.5’ diam. VSC @ 7’ OC, except last row BENT 1 www.subsurfaceconstructors.com

Pre- and Post-Treatment SPT Tests Results Bent 1, Structure 33 N > 8 N > 8 www.subsurfaceconstructors.com

Pre- and Post-Treatment SPT Tests Results Bent 2, Structure 34 N > 8 N > 8 www.subsurfaceconstructors.com

www.subsurfaceconstructors.com

I-69 Over CR 900E  Twin Bridges 55-Ft Long With MSE Wall Abutments  MSE Wall Approx. 25-Ft High From Leveling Pad  Liquefaction Analysis – OK Under Fill  Global Slope Stability Requires Stone Columns www.subsurfaceconstructors.com

I-69 Over CR 900E www.subsurfaceconstructors.com

I-69 Over CR 900E www.subsurfaceconstructors.com

I-69 Over CR 900E Cross Section Stone Columns Work Plan: • Diam = 3 ft. • Spacing = 8 to 9 ft. • Depth = 37 to 41 ft. www.subsurfaceconstructors.com

www.subsurfaceconstructors.com

Lessons Learned  Designing / Specifying Stone Columns What Is The Goal of Ground Improvement?  Specialty Contractor May or May Not Perform the Design  Specialty Contractor Should Be Consulted  Verification of Performance  Different Means and Methods to Construct www.subsurfaceconstructors.com

MSE Walls for MRB Approach  3 Large (up to 45ft) MSE Walls over I-70 in St. Louis  Bearing pressure = 3,500psf to 7,100 psf  Total Settlement = 2”  Global Slope Stability • FS (undrained) = 1.2 • FS (drained) = 1.5 www.subsurfaceconstructors.com

MSE Walls for MRB Approach www.subsurfaceconstructors.com

Transition Columns Slope Stability Concern Moved MSE Wall * Somes slides/pics complements of Dan Brown and Associates www.subsurfaceconstructors.com

More Critical Global Stability MSE Wall Pushed Out; Issue became Apparent Enter DBA. www.subsurfaceconstructors.com

General X-Section when DBA Arrived Max Wall Elev. 497’ or 47ft Tall MSE Strap Zone Transition Columns Stone Columns Bedrock www.subsurfaceconstructors.com

Analysis of West MSE Wall  Initially observed settlement of wall during construction (about 20ft of wall built)  Subsurface recommends staged construction in thirds (1/3 total height of wall)  Consultant analyzed global stability/soil strengths • FS(undrained) = 0.9 • FS (drained) = 1.6  Also observed some lateral movement of shorter wall where no stone columns installed www.subsurfaceconstructors.com

Wall pushed out. Movement occurred during installation of transition columns and stopped upon completion. www.subsurfaceconstructors.com

www.subsurfaceconstructors.com

Questions? www.subsurfaceconstructors.com