• NCDOT Geotech Alerts

    NCDOT Geotech Alerts for revisions and additions to standards are sent via an email distribution list.  Please provide your name and email to be added to the Geotechnical Distribution List.

     

  
  
  
  
  
  
Summary of Changes
Concrete Barrier Rail With Moment Slab DetailsRevised10/19/2021Cell
  • ​Adds note to align joints in rail with joints in wall facing​
Geotechnical Design Cell LibraryRevised10/19/2021Cell
  • ​Adds Wall ID with corresponding instructions to structure borders​
Geotechnical Foundation TablesMemo LinkNew10/19/2021Form
  • ​Microsoft Excel sheet with geotechnical foundation tables for the Structure plans
  • Includes tables for pile, drilled pier, spread footing and micropile foundations
17Micropiles (LRFD)Revised10/19/2021Provision
  • ​Adds option for ASTM A252 reinforcing casing with 80 ksi yield strength​
3,4,5,6MSE, Anchored, Soil Nail and Soldier Pile Retaining Walls (LRFD)Revised10/19/2021Provision
  • Redefines H, "Design Height  and "Wall Height"
  • Adds geostrip reinforcement for MSE walls
  • Adds black base cap for paving on aggregate above and behind MSE, anchored and soldier pile walls
  • ​Changes pH requirement for PET geogrid reinforcement for MSE walls from 5-8 to 4.5-9
  • Updates seismic design criteria for MSE walls to be consistent with other previously updated wall provisions and current AASHTO & NCDOT Structures Management policies/guidelines
  • Adds requirement that PP geogrids for MSE walls be made in the USA
  • Eliminates HDPE bearing pads from MSE walls with panels
  • Sets minimum steel gauge and grade for steel strip connectors for MSE walls with panels
  • Clarifies measurement and payment for backfilling behind MSE, anchored and soldier pile walls
  • Updates Soil Nail Retaining Walls provision for the latest editions of the AASHTO LRFD Bridge Design Specifications and AASHTO LRFD Bridge Construction Specifications
SP04 R005PilesMemo LinkNew10/19/2021Provision
  • Makes changes to Section 450 to implement new geotechnical foundation tables and pile order lengths for all prestressed concrete piles​
10Rock EmbankmentsRevised10/19/2021Provision
  • ​Updates measurement and payment to avoid duplicate pay items in contracts
453.01Standard CIP Gravity Retaining WallRevised10/19/2021Detail
  • ​​Redefines H, "Design Height" and "Wall Height"​
Standard Foundation Notes (LRFD)Revised10/19/2021Notes
  • ​​Adds new reworded pile sleeves note that was removed from MSE wall notes
  • ​Removes about half the standard foundation notes and rewords some others for the new geotechnical foundation tables
Standard MSE, Anchored, Soil Nail, Soldier Pile, Precast and Segmental Gravity Wall CellsRevised10/19/2021Cell
  • ​Redefines H, "Design Height" and "Wall Height"
  • Relabels "Backfill" material as "Retained" material for MSE, precast and segmental gravity walls
  • Adds geostrip reinforcement for MSE walls
  • Adds black base cap for paving on aggregate above and behind MSE, anchored and soldier pile walls​
Standard MSE, Anchored, Soil Nail, Soldier Pile, Precast and Segmental Gravity Wall NotesRevised10/19/2021Notes
  • ​Redefines H, "Design Height" and "Wall Height"
  • Relabels "Backfill" material as "Retained" material for MSE, precast and segmental gravity walls
  • Adds seismic note for MSE walls ​for consistency with changes to MSE Wall provision​ for seismic criteria
  • ​Removes pile sleeves note from MSE wall notes and adds new reworded pile sleeves note to standard foundation notes
454.01,02Standard Segmental Gravity Retaining WallsRevised10/19/2021Detail
  • ​​Redefines H, "Design Height" and "Wall Height"
  • Increases maximum wall height to 5 ft by increasing minimum wall batter and moving traffic surcharge further behind wall face​
11,12Standard Shoring and Temporary Soil Nail WallsRevised10/19/2021Provision
  • ​Updates Temporary Soil Nail Walls provision to reflect previous and current applicable updates in the Soil Nail Retaining Walls provision
  • ​Adds hollow bar nails as an option for temporary soil nail walls
  • Updates neat cement grout requirements for temporary soil nail walls to be consistent with changes made previously in the Soil Nail Retaining Walls provisions
  • Updates Standard Shoring provision ​​for changes to NCDOT Geosynthetic Reinforcement Evaluation Program
1801.02Standard Temporary WallRevised10/19/2021Detail
  • ​Updates notes on sheet 2 to reflect changes to NCDOT Geosynthetic Reinforcement Evaluation Program
SP11 R002Temporary ShoringRevised10/19/2021Provision

  • Updates neat cement grout requirements to be consistent with changes made previously in the Anchored Retaining Walls provision
  • Updates Standard Shoring provision ​​for changes to NCDOT Geosynthetic Reinforcement Evaluation Program​​

17Micropiles (LRFD)New4/21/2020Provision
  • ​Standardizes current Micropiles Project Special Provision
  • Requires the use of a prequalified Micropile Contractor and a prequalified Micropile Design Consultant
  • Conforms to current AASHTO LRFD Bridge Design Specifications for LRFD micropile design
  • Uses nominal wall thickness for reinforcing casings
  • Conforms to current AASHTO LRFD Bridge Construction Specifications for micropile load testing
  • Specifies prime mill certified steel pipes for reinforcing casings that meet NCDOT "Buy American" requirements
Standard Micropile NotesNew4/21/2020Notes

  • ​Standardizes current micropile notes on plans to be consistent with new Micropiles (LRFD) provision
Anchored and Soil Nail Retaining Wall CellsRevised12/17/2019Cell
  • ​Adds seismic note to Anchored Wall and Soil Nail Wall Cells with standard notes
3,5,6Anchored, Soldier Pile and Soil Nail Retaining Walls (LRFD)Revised12/17/2019Provision
  • Updates Anchored and Soil Nail Wall Provisions for 2018 Standard Specifications
  • Updates Soildier Pile Wall Provision for consistency with Anchored Wall and Soil Nail Wall Provisions
  • Revises seismic criteria for anchored and soil nail walls to meet AASHTO and Structure Management Unit requirements
  • Changes grout requirements for ground achors and soil nails to be consistent with Structure Bulletin and AASHTO soil nail wall ballot items
  • Incorporates LRFD design for soil nail walls through AASHTO soil nail wall ballot items
  • Incorporates Slide and new Snail software programs for soil nail wall analysis and design verification
  • Incorporates AASHTO LRFD Bridge Construction Specifications for soil nail wall materials, corrosion protection and nail testing through AASHTO soil nail wall ballot items
  • Clarifies traffic impact requirements for soil nail wall design
Geotechnical Summary TablesRevised12/17/2019Form
  • ​​Adds new table for horizontal drains
SP08 R017Horizontal DrainsNew12/17/2019Provision
  • ​Creates new provision for horizontal drains with or without drain pipes to drain water from slopes and rock cuts and from behind retaining walls
8Reinforced Soil SlopesRevised12/17/2019Provision
  • ​Revises provision for new Geosynthetic Reinforcement Evaluation Program (formerly called Geogrid Evaluation Program)
  • Updates link for list of approved geosynthetic reinf. (list was moved from the M&T website to the Geotech website) for primary geogrids
  • Adds requirement for American made biaxial geogrids for secondary geogrids
  • Increases minimum width/length of secondary/primary geogrids to 6'
  • Removes option for splicing primary geogrids
Standard Anchored and Soil Nail Retaining Wall NotesRevised12/17/2019Notes
  • ​Adds seismic note for consistency with changes to Anchored Wall and Soil Nail Wall provisions for seismic criteria
817.01Standard Horizontal DrainNew12/17/2019Detail
  • ​Creates new standard detail for horizontal drains with or without drain pipes to drain water from slopes and rock cuts and from behind retaining walls
1802.01,02Standard Reinforced Soil Slope with High Groundwater, Standard Reinforced Soil Slope with Low GroundwaterRevised12/17/2019Detail
  • ​Revises detail for new Geosynthetic Reinforcement Evaluation Program (formerly called Geogrid Evaluation Program)
  • Updates link for list of approved geosynthetic reinf. (list was moved from the M&T website to the Geotech website) for primary geogrids
  • Adds flood elevation to notes on High GW RSS detail
  • Increases minimum width/length of secondary/primary geogrids to 6'
  • Removes option for splicing primary geogrids
SP05 R008Aggregate SubgradeNew5/15/2018Provision
  • ​Designates current aggregate subgrade in Section 505 as a Type 1 Aggregate Subgrade and adds a Type 2 Aggregate Subgrade
  • Includes thickness, proofrolling, compaction and undercutting requirements for each aggregate subgrade type
SP05 R017Class IV Subgrade Stabilization in Lieu of Chemical StabilizationRevised5/15/2018Provision
  • ​Adds proofrolling requirement and aggregate subgrade type for Class IV Subgrade Stabilization
Geotechnical Summary TablesRevised5/15/2018Form
  • ​Revises Summary of Aggregate Subgrade/Stabilization table to accommodate both aggregate subgrade types
7Geotextile for Pavement StabilizationRevised5/15/2018Provision
  • ​Adds proofrolling requirement and aggregate subgrade type for Class IV Subgrade Stabilization
SP04 R002BAlternate Bridge Approach Fills for Integral AbutmentsNew1/16/2018Provision
  • ​Addresses new bridge approach fill for integral abutments (2018 Roadway Standard Drawing No. 422.03)
  • Includes Contractor's option for new Type A Alternate Approach Fill for Integral Abutments
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