1809 HOLBROOK AVE 2018-01-02 MF Import

Terhune Homes, Inc. JN 99028 February 25, 1999 Page 4 If the ground in front of a foundation is loose or sloping, the passive earth pressure given above will not be appropriate. We recommend a safety factor of at least 1.5 for the foundation's resistance to lateral loading, when using the above design values. Seismic Considerations The site is located within Seismic Zone 3, as illustrated on Figure No. 16-2 of the 1997 Uniform Building Code (UBC). In accordance with Table 16-J of the 1997 UBC, the site soil profile is best represented by Soil Profile Type Sp (Stiff Soil). The site soils are not subject to seismic liquefaction because of their dense nature. Permanent Foundation and Retaining Walls Retaining walls backfilled on only one side should be designed to resist the lateral earth pressures imposed by the soil they retain. The following recommended design parameters are for walls that restrain level backfill: Parameter Design Value Active Earth Pressure 35 pcf Passive Earth Pressure 300 pcf Coefficient of Friction 0.40 Soil Unit Weight 130 pcf where: (i) pcf is pounds per cubic foot, and (II) active and passive eartl pressures are computed using the equivalent fluid pressures. For a restrained wall that cannot deflect at least 0.002 times Its height, a uniform lateral pressure equal to 10 psf limes the height of the wall should be added to the above active equivalent fluid pressure. The values given above are to .e used to design permanent foundation and retaining walls only. The passive pressure given is appropriate for the depth of level structural fill placed in front of a retaining or foundation wall only. We recommend a safety factor of at least 1.5 for overturning and sliding, when using the above values to design, the walls. Restrained wall soil parameters should be utilized for a distance of 1.5 times the wall height from corners in the walls. The design values giver) above do not include the effects of any hydrostatic pressures behind the walls and assume that no surcharges, such as those caused by slopes, vehicles, or adjacent foundations will be exerted on the walls. If these conditions exist, those pressures should be added to the above lateral soil pressure::. Where sloping backfill is desired behind the walls, we will need to be given the wall dimensions and the slope of the backfill in order to provide the appropriate design earth pressures. The surcharge due to traffic loads behind a wall can typically be accounted for by adding a uniform pressure equal to 2 feet multiplied by the above active fluid density. GEOTECH CONSULTANTS, INC.