Design Assumptions for Geogrid Reinforced Segmental Walls

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Design Assumptions for Geogrid Reinforced Segmental Walls

When working with the Geogrid Reinforced Segmental Retaining Wall module in RetainPro the input screens and output report vary from the conventional cantilevered and restrained retaining walls.


In general, methodology used conforms to NCMA’s Design of Segmental Retaining Walls, 3rd Edition.  


Since segmental geogrid reinforced retaining walls can be highly complex, some simplifying design assumptions have been implemented to make the program easier to use and still cover most conditions encountered. These assumptions are:


1.All masonry units are the same size (height, width, depth) and single wythe.

2.Offsets between blocks are uniform for the full height of the wall.

3.Spacing of geogrid layers may be specified (number of blocks between layers), but spacing is constant except for lowest layer and above uppermost layer.

4.Lengths of geogrids are constant for all layers.

5.Same geogrid material is used for all layers.

6.Coulomb method is used for determining lateral earth pressures.

7.Overall wall height is limited to 30 feet.

8.Setting base is assumed to be gravel or crushed stone, 6” thick, and extending 6” beyond each edge of the bottom block.

9.Block dimensions are obtained from vendor websites or literature.

10.Weight of wall is assumed to be 120 pcf for depth of block.

11.Geogrid Long Term Design Strength and connection values have been obtained from vendor websites or vendor ES-ICC Evaluation Reports. Verification with vendor is recommended.