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Gcotcchnical Gnginr,cring Rcport <br /> llousingliopc <br /> December 5,200d <br /> RMl File No. 2170d <br /> Page I1 <br /> may oe calculaled as a triangular equivale�t fluid pressure distribution. An equi�'alent Fluid <br /> densiry of 200 pounds per cubic foot(pcQ should be user for passivc resistance design for a levcl <br /> ground surface adjucent to the footing. This levcl surface should extend to a distance equal to at <br /> Icast three times the depth to bcaring of thc footing. These rccommended valucs incorporatc <br /> safety factors of 1.5 and 2.0 applied to die estimated ultimate valuea for frictional end passive <br /> resistance, respectively. To achieve this value of passive resistance, the founda[ions should be <br /> poured "neaY' against the native medium dense soils or compacted fill should be used as bxkfill <br /> against the front of the footing. We recommend that the upper 1-foot of soil be neglected when <br /> calculating the passive resistance. <br /> Tablc A <br /> A roximatc Dc th to Suitablc Bcarin Soil & Bearin Soil T � c <br /> Test Pit Depth ro Bearing Soil" Bearing Suil Type(USCS) Depth of O nsf e1)Seepage <br /> in feet) <br /> T�,_� q,p SP-SM None <br /> TP-2 3.0 SP-SM None <br /> TP-3 ` <br /> T�,� p� SP-Slvl None <br /> USCS—Unified Soil Clnssification 5����em(definition oFsyTnbols used) <br /> SM—Silty Sand SP-SM—Sand With Silt <br /> SP—Poorty-Graded Sand GP—Poorly-Graded Gravel <br /> SW—Well-Graded Sand GW—Well-Graded Grnvel <br /> 'Abandoned rior to encounrerin benrin soil due to encountering shallow drninaGe treneh. <br /> Subsurface and Retaining `rValls <br /> The lateral pressurc acting on subsurface and rer.iining walls is dependent on the nature and <br /> density of the soil behind the �vall, the amount of lateral wall movemen[ which can occur as <br /> backfill is placed, wall drainage conditions, and the inclination of the backfill. For walis that are <br /> 1'rce to yicld at tlre top at Icast one thousandth of the height of the wall (active condition), soil <br /> pressures will be less than if movement is limited by such facrors as wall stiffness or bracing(at- <br /> rest condition). We recommenJ that walls supporting horizontal backfill and not subjected to <br /> hydrostatic forces be designed using a triangular earth pressure distribution equivalent ro that <br /> cscrted by a fluid with a density of 35 pcf for yielding (active condition) walls, and 60 pcf for <br /> non-yielding(at-rest condition)walls. <br /> RM! aSSOCtATES, LTD. <br /> L- <br />