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I I I I I I I I I I I I I I I I I I I Simons, Li and Associates, Inc. Job. No. 6143J002 project: Portland Flume Reconstruction Recommendations for structural elements supported on compacted fills or prepared subgrade are dependent upon satisfactory site preparation and the placement and compaction of subsequent fill zones. Therefore, earthwork relative to structural support should be accomplished under observation and testing directed by the geotechnical engineer. Observation and testing should also be provided during excavation and during the placement and compaction of all backfill. Lateral Earth Pressures: Recommended lateral earth pressure values are presented in the following tabulation: Equivalent active soil pressure: Undisturbed subsoil ------------------- 35 psf/ft Compacted backfill {on-site or imported soils)------------ 30 psf/ft Equivalent passive soil pressure: Shallow wall/wall footings ------------250 psf/ft Shallow columns/column footings -------325 psf/ft Drilled Caissons-----------------------450 psf/ft Equivalent at-rest soil pressure: Shallow wall/wall footings--------------45 psf/ft. Base friction coefficient ------------ 0.30* *The coefficient of base friction should be reduced to 0.20 when used in conjunction with passive pressure. The at-rest soil pressures should be used for structures with rigid, restrained, relatively unyielding walls, such as the box culverts. Fill against footings, box culverts, basement walls, and flume walls should be placed to densities specified in "Site Prep- aration" to minimize total active pressures and to develop pas- sive resistances at relatively low strains. -6-