622.1 General Description
This work consists of performing the global stability analyses of applicable retaining walls after final construction plans, shop drawings and design notes have been developed, reviewed and approved. Perform this work before the wall is constructed. This work shall be performed by a Professional Engineer licensed in the state of Georgia who is experienced in this type of work.
622.2 Applicable Wall Types
This specification applies to the following wall types: 1. Rigid/Cantilever Retaining Walls 2. Gravity Walls 3. Mechanically Stabilized Embankment Retaining Walls 4. Mechanically Stabilized Embankment Retaining Wall – Contractor Design 5. Soldier Pile Walls with or without Anchors 6. Soil Nail Walls Note: GDOT Standard Walls are excluded from the requirements of this special provision.
622.3 Criteria for Global Stability Requirement
Perform global stability analyses on construction for Walls that meet any of the following criteria: 1. Wall Height is 15 ft. or greater. 2. Wall is being constructed on a slope. 3. Wall will have a slope, structure (including structures attached directly to the top of the wall such as sound walls), or traffic loading above it. 4. Wall footing is being constructed on weak underlying soils with the following conditions: • Soils within 10 ft. of the bottom of footing are single digit blow count soils based on SPT tests. • Groundwater is within 5 ft. of the bottom of the wall.
622.4 Requirements
Develop the shop drawings for the wall and submit the drawings to the Department for review and approval prior to performing field global stability analyses. Use the subsurface investigation data from the approved Wall Foundation Investigation (WFI) report for global stability analyses. Any additional borings performed on construction may be used for global stability analyses. For MSE Walls, use the properties of the backfill material as well as the strap lengths shown on the shop drawings for global stability analyses, even if they differ from that which was specified on the approved WFI. Model the wall in the global stability analysis program using the exact wall configuration to be built on construction. Identify all critical sections of the Wall such as the tallest sections, sections on slopes, sections with a slope, structure or traffic loading above the wall, and sections on the weakest soils, and analyze these sections for global stability. All global runs shall meet the requirements of AASHTO LRFD Specifications, Seventh Edition, 2014 – Section 11.6.2.3. For walls that do not meet the requirements, provide recommendations to mitigate the problem, and submit global stability analyses that incorporate the recommended solution(s). All global runs that incorporate the solutions shall meet the AASHTO LRFD requirements. Prior to implementing a solution on construction, receive approval from the Geotechnical Bureau. Submit a global stability analyses report with analyses and recommendations (if warranted) to the Office of Materials and Testing’s Geotechnical Bureau for review and approval before wall construction commences. Allow seven (7) calendar days for review and approval. Provide global stability analyses and recommendations (if warranted) using the services of a Professional Engineer licensed in the state of Georgia who is experienced in this type work.
622.5 Payment
No separate payment will be made for performing global stability analyses or any associated tasks deemed necessary such as additional investigation or report preparation. Include the cost of this work in the contract bid price for the retaining wall.
Get an email when 622 changes
Georgia revises spec sections through supplementals and new editions. We check this one every week and email you the day it changes. Free, no account.