1230 MADRONA AVE 2016-01-01 MF Import

April 10, 2005 1'roposed Single-Pamily Residence I,&A JoU No. SA019 Pagc 13 resistlnce. 'I'he �bove passive pressure assumes that the Uackfill is ]evel or inclines upward lway from the foundations for a horizontnl distance at least hvicc thc depth of the foimdations belo�i� the finn] grade. A coeffici�nt of friction of 0.60 between the fowidations and the subgrade soils may be used. 7'he above soil par;�metcrs are unf�ctored values, and � proper factor of safety sUould be used in c�lculnting the resisting forces againsi lateral lo:�ds on the buildings. I3AS�MEN7' AND RI'sTAIMNG �1'AI.LS 13nsement walls reslrained horizontally at thc top arc considered unyielding and should be designed for a latcral soil pressurc tmder tl�c tit-rest condition; �vhile retaining ��alls frce to movc at llic top should be desig»ed for active latcral soil pressure. ��c recommend that a latera] soil pressurc of 45 and (5 pcf L'['D be used for thc design of foundation walls with level/descending backslopc and rising backslope, respcctivcly; and 35 and 50 pcf T'PD for re:aining walls �1�ith IcveUdescending backslope and rising backslope, respec�ively. To cotmter the acti��e soil or at- rest pressurc, a passivc laternl soil presswe of 350 pcf L'1'D may bc used, escept that the passive pressure within the top 12 inclics of ihc finish subgrnde should be ignored. The abovc passivc pressurc asstnncs that lhc bacl<fill is Icvcl or inclincs upward away Gom thc �valls. 7'hc above lateral soil pressures arc under thc assumption that ground��-atcr bchinc! the ��alls is fully drained. To resist agninst s(iding, thc friction force between thc footings and ihc subgrlde soils may be c�lculated bascd on a cocfficicnt of li�iclion of 0.00. 71�c abo��e soil parameters arc ultimate v.ilucs, and proper factors of safety should be used in the design of the Uasement and retaining walls against sliding and overturning faihires. i3�isement walls or retlining walls mny be supporled on footing foundalions scatcd on or into the underlying dense to vep�-densc, silty fine to medimn sand soils in tire transition zone or in ihe ��ery-stiff to vcry-hard, fine sandy silt to claycy silt soils of tl�c Older Cla�� unil, with an �Ilowable soil bearing pressure not to exceed �,500 psf. L1U & ASSOCIAT�S, INC.