Backfilling, Compaction, and Geogrid Layering on Slopes

What happens here

After each course of retaining wall blocks is laid, the area behind the wall is backfilled. This involves placing drainage aggregate directly behind the blocks to facilitate water flow, followed by structural fill soil. Geogrid is then strategically laid on top of the soil backfill at specified intervals, typically after every two courses of blocks, extending back into the slope to anchor the wall. Each layer of soil and geogrid, known as a 'lift,' must be thoroughly compacted to achieve optimal density and stability. Initially, a plate compactor is used to smooth out the layer and remove rough bumps. For deeper and more effective compaction of the soil, especially in tight or sloped areas, a sheep's foot compactor (or trencher compactor) is used. The skid steer is also used to mix and moisten the dirt to ensure the ideal moisture content for compaction, as proper moisture is crucial for achieving maximum density. This process of layered backfill, geogrid, and compaction is vital for the long-term stability and load-bearing capacity of the retaining wall on a steep slope, particularly when anticipating future height adjustments.

Goal: This step outlines the critical process of backfilling behind the retaining wall with drainage aggregate and soil, followed by meticulous compaction of each lift. It emphasizes the strategic layering of geogrid to reinforce the wall and prepare it for the stresses of a sloped environment and potential future height increases.