Mandatory Checklist for Mechanically Stabilized Earth Retaining Wall Foundation Design.

Designing the foundation for a Mechanically Stabilized Earth (MSE) retaining wall involves considerations for stability, bearing capacity, and soil-structure interaction. Below is a detailed checklist with explanations and examples for the design of an MSE retaining wall foundation:

1. Site Investigation:

Explanation: Conduct a thorough site investigation to understand soil conditions.
Example: Perform soil tests (SPT, CPT) to determine soil properties, bearing capacity, and potential sliding or settlement.

2. Load Analysis:

Explanation: Analyze and calculate loads acting on the MSE retaining wall.
Example: Consider the weight of the wall, backfill soil pressure, surcharge loads, water pressure, and seismic loads to determine the total lateral load.

3. Bearing Capacity:

Explanation: Ensure that the soil bearing capacity is sufficient for the applied loads.
Example: If the total lateral load is 150 kN/m and the soil bearing capacity is 300 kN/m², the foundation is considered suitable.

4. Sliding Stability:

Explanation: Check and ensure the foundation resists sliding.
Example: Calculate the sliding force and compare it to the resisting force provided by the foundation. Use appropriate safety factors.

5. Foundation Geometry:

Explanation: Determine the appropriate dimensions and shape of the foundation.
Example: Design a foundation with proper width, length, and reinforcement to distribute the loads evenly along the length of the MSE retaining wall.

6. Reinforcement:

Explanation: Specify reinforcement in the foundation and MSE wall, if required.
Example: Include geogrid reinforcement layers within the backfill to enhance the MSE wall’s stability and improve overall performance.

7. Foundation Depth:

Explanation: Determine the optimal foundation depth for stability.
Example: Increase the foundation depth if weak or compressible soil layers are present near the surface.

8. Drainage:

Explanation: Implement drainage measures to reduce hydrostatic pressure.
Example: Install drainage pipes or geocomposite drains behind the MSE wall to relieve water pressure and prevent water accumulation.

9. Backfill Specifications:

Explanation: Specify backfill material properties and compaction requirements.
Example: Use granular backfill material with proper gradation and compaction to achieve the required density and frictional resistance.

10. Facing Connection:

Explanation: Detail the connection between the MSE facing and the foundation.
Example: Ensure that the facing panels or blocks are securely attached to the foundation using appropriate connectors.

11. Construction Sequence:

Explanation: Develop a construction sequence that ensures stability during and after construction.
Example: Place and compact the foundation material, install the geogrid reinforcement layers, construct the MSE wall facing, and ensure proper compaction of the backfill.

12. Quality Control:

Explanation: Implement quality control measures during construction.
Example: Monitor the compaction of backfill, check reinforcement placement, verify the dimensions of the foundation, and ensure proper facing installation.

13. Code Compliance:

Explanation: Ensure compliance with local building codes and standards.
Example: Adhere to relevant codes such as AASHTO LRFD Bridge Design Specifications or local geotechnical standards.

14. Professional Engineer Involvement:

Explanation: Engage a qualified geotechnical and structural engineer to oversee the design.
Example: Have licensed engineers review and approve the MSE retaining wall foundation design to ensure it meets safety and code requirements.

15. Record Keeping:

Explanation: Maintain detailed records of the MSE retaining wall foundation design process.
Example: Document all design calculations, soil test results, construction activities, and as-built drawings for future reference and audits.

By following this checklist, engineers can ensure a well-designed MSE retaining wall foundation that effectively resists lateral loads, provides stability, and minimizes potential failure modes.