3003 W CASINO RD BLDG 40-58 Geotech Report 2022-10-25

t The equivalent fluid densities presented above do not include additional loading due to adjacent surcharge loads, such as will occur due to a loaded concrete slab in the manufacturing area. We understand that the floor slab may experience a working load of up to 500 psf A minimum surcharge pressure of 250 psf should be assumed when estimating the additional load on below-grade walls adjacent to parking areas and traveled roadways. When these or other distributed surcharge loads are present, additional lateral earth pressure will be applied against below-grade walls. For non-yielding walls, this additional lateral earth pressure increase may be estimated as 41 percent of the applied vertical distributed surcharge pressure. For yielding walls that can tolerate deflection,the lateral pressure may be estimated as 27 percent of the vertical distributed surcharge pressure. To prevent the buildup of hydrostatic pressure in the backfill behind below-grade walls, a wall footing drainage system should incorporated into the design. We recommend that wall drainage be provided at an elevation no higher that the retaining wall subgrade elevation, and that the drain consist of a slotted or perforated pipe surrounded by an envelope of free-draining gravel (pea gravel or similar) extending a minimum of 6 inches on all sides of the pipe. The gravel envelope should be encapsulated by a non-woven separation geotextile to reduce the migration of fines into the wall drainage system. Depending upon the location, additional wall drainage and a waterproofing layer (such as a sprayed bituminous coating or peel-and-stick membrane) and a composite drainage board discharging to the footing drain may be necessary. However, wall locations with an interior retained "high-side" could consider just a waterproofing layer. 3.12 DYNAMIC LATERAL EARTH PRESSURES Dynamic lateral earth pressures should be included in the design of below grade walls. A lateral pressure distribution consisting of an inverted trapezoid should be added to the static lateral earth pressures for all yielding and non-yielding) walls. For non-yielding walls with a level backslope and restrained against rotation and translation during a strong motion earthquake,the trapezoid has a pressure distribution (in psf) equivalent to 58H at the top (where H is the height of the wall) and 15H at the bottom. We assume that the north building wall, which supports superstructure columns, will need to be non-yielding during an earthquake. Tunnel walls and utilidor walls may also act as non-yielding structures. For walls that have a level backslope and that will be free to rotate and translate laterally on the order of 2 inches during a strong motion earthquake, a trapezoidal pressure distribution may be assumed with a pressure ordinate (in psf) at the top-of-wall of 14H; the bottom-of-wall ordinate may be assumed to be 3.5H. 5/16/14 P:U 423\002\O10\FileRm\R\Draft Bldg 40-58 Report\Bldg 40-58_draft rpt.docx INTERIM D RA F T 3-11