RETAINING WALL DESIGNSLOPE STABIL ITY ON US-189MAQUIGR ENGINEERING

Matthew Hakes, Quinton Taylor, Greg Hanks

PICTURE OF (SITE)CAPSTONE TEAM WHO WE ARE (MEMBERS SKILLS)MAQUIGR TEAM BEYONDSHOWS FRACTURED ROCKSPICTURES DISPLAYED

Site Evaluation

Site 1

Site 2

SITE 1 IS FEATURED ON TOPSITE 2 ON BOTTOMNOTICE:WATER LOCATIONTEMPORARY SOLUTIONS LOADS CAUSED BY ROAD

Considered Solutions

Sheetpile Tieback

ShotcreteSoil Nail

Gabion Tieback

SHEET PILE PROS RAPID CONSTRUCTIONCONS SHALLOW ROCK MAKES IT IMPOSSIBLE TO DIG IN DEEP ENOUGH TO GET MOMENT

Analysis with SnailPlusAssumptions 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

Under normal traffic loads

Design section Calculation FS Slope Fmax Nails (k) Fmax Nails at Head (k) STR Check Nails STR Check Plates STR Check Facing

No. 4 Calculation successful 1.347 17.3 17.3 0.296 0.89 0.286

No. 3 Calculation successful 2.155 6.8 6.8 0.117 0.353 0.113

Design section Calculation FS Slope Fmax Nails (k) Fmax Nails at Head (k) STR Check Nails STR Check Plates STR Check Facing

No. 4 Calculation successful 1.579 14.9 14.9 0.257 0.856 0.275

No. 3 Calculation successful 3.07 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 SHAPECREATED SLOPE IN AUTO CADUNIFIED DESIGN 1/2 THE DISTANCE FOLLOW SLOPE OR WHATOPTIMIZED FOR CONSTRUCTION

Phase 1•Conducted during low traffic flow•Close southbound lane•Flaggers to direct flow of trafficthrough single lane

Environmental Impact Reduction (3 lines of defense)•Excavated 5ft bench •1ft silt fence installed 20ft below excavation line•Exposed Shoreline

Site Preparation

Phase 2•5ft bench approximately 10ft out from edge of the road•Excavation of 1,000 cubic feet •Soil relocated to holding site

Excavation Slope Preparation

Phase 3•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

Soil Nail Installation

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

Prefabrication of Rebar Cages

Phase 5•Challenge will be mobility and visibility of excavator

•Guided into place by multiple workers located on bench

Installing Rebar CagesThe key to the project was contstruction speed

8 in mat Number 6 rebarTied together

Bring in on flat bead and then drop in excavator secure them in place

Phase 6

•Two step process using wire mesh as backstop for shotcrete

•First day application spraying towards the road, second day other side is applied

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

Phase 8•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

Anchor to wall Attachments

Phase 9•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

Backfill

Phase 10 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

Capping Phase 11 Cleanup

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

•Cost estimates are based on the FHWA pricing graph and scheduling was created in 11 phases

Days 17Plans & SurveyingPermits & Fees Construction Loans

1Phase 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Staging areaSilt FencingMoving BaricadesTraffi c Control Laying gravel Construction Signage

Phase 2 Staking ExcavationSoil Removal

Phase 3 Marking Soil Nail Instalationdrillingadd section groutingcapping

Phase 4 Delivery Rebar, TiesCutting Bending rebartieing rebarInstalling wire meshloading for transit

Phase 5 Drainage FabricDrainage Piping

Phase 6 Marking LocationLeveling Compacting basedelivering from stagingdropping in placeIn place fabricationsecuring soil nails

Phase 7 Shotcreting walls

Phase 8 Attachmen plates

Phase 9 Load for backfillTransport backfillPlace BackfillCompact 10" lifts

Phase 10 Form for concrete cap Pour concrete

Phase 11 CleanupRemoving Traffi c devices

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

COST THE FEDERAL HIGHWAY ADMINISTRATIONCHARCTERISTICS THAT COST $$$LOCATION, MATERIAL, NIGHT TIME ECTSCHEDULE HOW WE CAME UPINTEGRATING PHASES TO OPOMIZE TIME

ConclusionA 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