Presentation - The BYU Civil and Environmental Engineering

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Transcript Presentation - The BYU Civil and Environmental Engineering

RETAINING WALL DESIGN

S LO P E S TA B I L I T Y O N U S - 1 8 9 M A Q U I G R E N G I N E E R I N G Matthew Hakes, Quinton Taylor, Greg Hanks PICTURE OF (SITE) CAPSTONE TEAM WHO WE ARE (MEMBERS SKILLS) MAQUIGR TEAM BEYOND SHOWS FRACTURED ROCKS PICTURES DISPLAYED

Site Evaluation

Site 1 Site 2 SITE 1 IS FEATURED ON TOP SITE 2 ON BOT TOM NOTICE: WATER LOCATION TEMPORARY SOLUTIONS LOADS CAUSED BY ROAD

Considered Solutions

SHEET PILE PROS RAPID CONSTRUCTION CONS SHALLOW ROCK MAKES IT IMPOSSIBLE TO DIG IN DEEP ENOUGH TO GET MOMENT Gabion Tieback Sheetpile Tieback Shotcrete Soil Nail

Analysis with SnailPlus

Assumptions made: Two different soil types • Gravel/Sand • Bedrock Loading • Temporary Max: 700 psf from construction • Permanent Max: 200 psf from traffic Morgenstern-Price • General limit equilibrium (Moment-force) FHWA factors of safety used

Analysis with SnailPlus

Under construction loading conditions Design section Calculation No. 4 No. 3 Calculation successful Calculation successful Under normal traffic loads FS Slope 1.347

2.155

Fmax Nails (k) 17.3

6.8

Fmax Nails at Head (k) 17.3

STR Check Nails STR Check Plates STR Check Facing 0.296

0.89

0.286

6.8

0.117

0.353

0.113

Design section FS Slope Fmax Nails (k) Fmax Nails at Head (k) 14.9

STR Check Nails STR Check Plates STR Check Facing 0.257

0.856

0.275

No. 4 No. 3 Calculation Calculation successful Calculation successful 1.579

3.07

14.9

5.5

5.5

0.094

0.331

0.09

Final Design

• 10ft from road edge • 120ft in length • 17 Total Soil Nails • Average height, 6ft • Max height, 13ft INITIAL CONCEPTION OF WALL SHAPE CREATED SLOPE IN AUTO CAD UNIFIED DESIGN 1/2 THE DISTANCE FOLLOW SLOPE OR WHAT OPTIMIZED FOR CONSTRUCTION

Phase 1 Site Preparation

• Conducted during low traffic flow • Close southbound lane • Flaggers to direct flow of traffic through single lane Environmental Impact Reduction (3 lines of defense) • Excavated 5ft bench • 1ft silt fence installed 20ft below excavation line • Exposed Shoreline

Phase 2 Excavation Slope Preparation

• 5ft bench approximately 10ft out from edge of the road • Excavation of 1,000 cubic feet • Soil relocated to holding site

Phase 3 Soil Nail Installation

• Williams Geo-Drill Injection Anchor System with rotary percussive drilling • In case of hitting hard rock, a Polyester Resin Rock Anchor System may be used

Phase 4 Prefabrication of Rebar Cages

Phase 4: • Constructed offsite due to limited space • 75 year design life, hot-dip galvanizing

Phase 5 Installing Rebar Cages

• Challenge will be mobility and visibility of excavator • Guided into place by multiple workers located on bench The key to the project was contstruction speed 8 in mat Number 6 rebar Tied together Bring in on flat bead and then drop in excavator secure them in place

Phase 6 Shotcrete

• Two step process using wire mesh as backstop for shotcrete • First day application spraying towards the road, second day other side is applied A problem (wall needs concrete) solution we could pump it with shotcrete Bench was created for workers to stand on No wall – wire mesh 2 sided

Phase 7 Installing Drainage System

Phase 5: • Composite Drainage system • Drainage system includes: geosythetic filtered fabric and molded plastic core

Phase 8 Anchor to wall Attachments

• Bearing plate, hardened washers, hex nut, and Geo-Drill Injection Anchor • 75 year design life, galvanizing bearing plate and hardened washers and capped with a steel tube filled with cement grout

Phase 9 Backfill

• Using the soil from the excavation, backfill at 8-12in lifts • Compact soil with plate compactor attachment while avoiding soil nails • Increased bar size to improve bending strength in the case of accidental contact with compactor

Phase 10 Phase 11 Capping Cleanup

Phase 10: • Last 4-6in of backfill will be filled with cement to cap off the retaining system • Reduce permeability of surface and prevent corrosion Phase 11: • Remove silt fencing and any loose material • Add soil to bench to create a more natural slope • Application of hydroseed to slope to promote vegetation growth

Time and Cost Estimates

Days Plans & Surveying Permits & Fees Construction Loans Phase 1 Staging area Silt Fencing Moving Baricades Traffic Control Laying gravel Construction Signage Phase 2 Staking Excavation Soil Removal Phase 3 Marking Soil Nail Instalation drilling add section grouting capping Phase 4 Delivery Rebar, Ties Cutting Bending rebar tieing rebar Installing wire mesh loading for transit Phase 5 Drainage Fabric Drainage Piping Phase 6 Marking Location Leveling Compacting base delivering from staging dropping in place In place fabrication securing soil nails Phase 7 Shotcreting walls Phase 8 Attachmen plates Phase 9 Load for backfill Transport backfill Place Backfill Compact 10" lifts Phase 10 Form for concrete cap Pour concrete Phase 11 Cleanup Removing Traffic devices 17 For this Project we will assume that Planning and Surveying, Permits and Fees and Construction Loans are taken Care of at this point. The Schedule will be 17 Days 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 COST THE FEDERAL HIGHWAY ADMINISTRATION CHARCTERISTICS THAT COST $$$ LOCATION, MATERIAL, NIGHT TIME ECT SCHEDULE HOW WE CAME UP INTEGRATING PHASES TO OPOMIZE TIME • Cost estimates are based on the FHWA pricing graph and scheduling was created in 11 phases

Conclusion

A soil nail retaining system is the best option for this project • Adaptable – Depending on what is encountered during construction this design can easily be modified to meet the needs of the project • Cost Effective – With little excavation near the road, a temporary wall will be unnecessary • 75 Design Life – Simple methods that can be implicated to increase design life