Mandatory Checklist for Hybrid Systems Retaining Wall Foundation Design.

Designing the foundation for a Hybrid Systems Retaining Wall involves integrating various retaining wall technologies. The checklist below outlines the key considerations with explanations and examples for the design of such a 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 hybrid systems 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 180 kN/m and the soil bearing capacity is 250 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 that integrates elements of different retaining wall systems, such as combining reinforced soil slopes with anchored walls.

6. Reinforcement:

Explanation: Specify reinforcement in the foundation, walls, and other components if required.
Example: Include geogrid reinforcement in the reinforced soil slopes and use tiebacks for additional reinforcement in the anchored walls.

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, considering the requirements of each retaining wall system.

8. Drainage:

Explanation: Implement drainage measures to reduce hydrostatic pressure.
Example: Install drainage pipes, geocomposite drains, or other drainage systems as needed behind the retaining wall components to ensure proper water management.

9. Backfill Specifications:

Explanation: Specify backfill material properties and compaction requirements for each retaining wall system.
Example: Utilize granular backfill with proper gradation and compaction for reinforced soil slopes, and choose suitable backfill for anchored walls based on soil conditions.

10. Facing Connection:

Explanation: Detail the connection between different facing elements and the foundation.
Example: Ensure secure connections between reinforced soil slope facings and anchored wall facings to create a cohesive and stable hybrid system.

11. Construction Sequence:

Explanation: Develop a construction sequence that ensures stability during and after construction.
Example: Coordinate the construction of different retaining wall components, ensuring proper sequencing to maintain stability and avoid disruptions.

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 installation of facing elements.

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 for each retaining wall system.

14. Professional Engineer Involvement:

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

15. Record Keeping:

Explanation: Maintain detailed records of the hybrid systems 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 foundation for a Hybrid Systems Retaining Wall that effectively integrates various retaining wall technologies, resists lateral loads, provides stability, and minimizes potential failure modes.