3632 RUCKER AVE THE LANDING AT PORT GARDNER Geotech Report 2023-04-10

Aug. 31. 2004 3:46PM CHARLES MORGAN & ASSOC. No. 0044 P. 6 . • Grandview Homes, LLC JN 99040 February 16, 1999 Page 4 All slabs-on-grade should be underlain by a capillary break or drainage layer consisting of a minimum 4-inch thickness of coarse, free-draining structural fill with a gradation similar to that discussed later in Permanent Foundation and Retaining Walls. In areas where the passage of moisture through the slab is undesirable, a vapor barrier, such as a 6-mil plastic membrane, should be placed beneath the slab. Additionally, sand should be used in the fine-grading process to reduce damage to the vapor barrier, to provide uniform support under the slab, and to reduce shrinkage cracking by improving the concrete curing process. Isolation joints should be provided where the slabs intersect columns and walls. Control and expansion joints should also be used to control cracking from expansion and•contraction. Saw cuts or preformed strip joints used to control shrinkage cracking should extend through the upper one- fourth of the slab. The spacing of control or expansion joints depends on the slab shape and the amount of steel placed in it. Reducing•the water-to-cement ratio of the concrete and curing the concrete, by preventing the evaporation of free water until cement hydration occurs, will also reduce shrinkage cracking. 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: a aroeter:: . Design Value Active Earth Pressure* 35 pcf Passive Earth Pressure 400 pcf Coefficient of Friction 0.40 Soil Unit Weight 140 pcf _ Where: (i) pcf Is pounds per cubic foot, and (li) active and passive earth 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 times the height of the wall should be added to the above active equivalent fluid pressure. The values given above are to be used to design permanent foundation and retaining wails 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 wails. The design values given above do not Include the effects of any hydrostatic pressures behind the walls and assume that no surcharges, such es 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 pressures. 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 SGEOTECH CONSULTANTS.INC. /