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STRATAGRID interacts with soil to form a stable foundation for SRW development.

Subgrade is graded flat in preparation for STRATAGRID placement.

STRATAGRID lies flat for easy installation.

Fill is placed onto STRATAGRID.

Figure 1: Cross Sectional View of Segmental Retaining Wall

Completed STRATAGRID Reinforced Segmental Retaining Wall at Pace Properties.

Background

Available property for development within the Interstate 285 perimeter in Atlanta is becoming increasingly scarce. A northwest portion of metropolitan Atlanta was becoming progressively more congested and sites previously considered too expensive or difficult to build upon were being targeted for development.

The owners wanted to develop this site for a motel/suites facility to accommodate overnight business travelers to this Atlanta neighborhood but the site was complicated by a deep ravine and limited right of way for grade separation and level construction.

A STRATAGRID reinforced slope and segmental retaining wall combination would offer a sufficient buildable area to allow placement of the hotel, while allowing limited strip shopping development alongside. This solution was chosen for its competitive pricing, attractive finished surface and minimal safety risks associated with the product’s installation and life span.

Design

Because of the complicated slope and wall structure selected for this project, analysis included not only internal reinforcement design for the Segmental Retaining Wall (SRW) but also slope stability analysis for the reinforced slope section. Reinforcement geogrids were extended back under the wall to ensure stability of the combined structure (see Figure 6).

Sheffer Engineering used StrataWALL software to design the STRATAGRID-reinforced SRW. External and global stability of the entire cross section was analyzed using slices. The critical failure surface passed behind and under the wall’s reinforced zone, a factor of safety of 1.5 for rotational stability was used.

Construction

The site was configured to optimize cut and fill, minimizing the need to haul fill in or out, although some select backfill soil was imported. Coordination of the earthmoving equipment with the STRATAGRID and SRW installation was the key to the efficient installation of this structure.

Wall construction progressed quickly with the SRW providing a stable work platform for the balance of the 38 foot height. A maximum of three block courses were used as vertical spacing (two feet) between geogrid reinforcement layers. This limitation helped solidify the stability of the constructed wall base.

In Summary

This STRATAGRID reinforced slope and segmental retaining wall combination allowed optimum flexibility in difficult grade separation site conditions while providing an attractive, low cost development solution. STRATAGRID helped the project meet its deadline, maximizing the development’s profitability by allowing it to open on schedule.

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