Geotechnical exploration/review-2008

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AMERICAN ENGINEERING TESTING, INC. AET Project No. 22-00012 next to the buildings. 6.6 Loading Docks The loading dock walls will act as short retaining walls, and we recommend that the walls be designed to resist the at-rest lateral earth pressure to reduce lateral deflection. The backfill behind the loading dock walls should be a granular soil with less than 12% passing the No. 200 sieve, placed in lifts, and compacted with manually-operated equipment to at least 95% of the maximum Standard Proctor dry density. The fill should be placed in lifts thin enough to attain the specified compaction level throughout the entire lift thickness. This normally requires that fill be placed in loose lifts less than 8 inches thick. For compacted sand backfill behind the walls, we recommend that the walls be designed to resist an equivalent fluid density of 50 pounds per cubic foot for the at-rest condition. For the active earth pressure condition, we recommend using equivalent fluid density of 35 pcf. The earth pressure should also include an additional uniform pressure equal to 0.5 times the uniform surcharge load applied over the interior wall backfill from the floor slab. The passive earth pressure at the base of the walls can be computed using an equivalent fluid density of 270 pounds per cubic foot. We recommend using a coefficient of sliding friction of 0.28 for mass concrete on cohesive soils. To achieve a higher coefficient of sliding friction, you could consider subcutting the cohesive soils at least 1 foot below the bottom of footing and replacing it with compacted sand backfill. We recommend using a coefficient of sliding friction of 0.50 for mass concrete on granular soils. A factor of safety of 1.5 should be used for the sliding resistance. Adequate vertical insulation should be placed on the inside face of the loading dock walls to prevent horizontal frost penetration into the interior floor slab subgrade. Page 18 of 28