7815 E GLEN DR 2016-01-01 MF Import

12.1 Passive Resistance and Friction Factors Retaining wall footings/keyways cast direc.tly against undisturbed, medium dense to dense natural sediments or properly compacted structural fill may '�e designed for passive resistance against lateral translation using an equivalent fluid equal to 250 pcf. Tt,e passive equivalent , fluid pressure diagram begins at the top of the footing; however, total lateral resistance should be summed onl}� over the depth of the actual key (wncated triangulaz diagram). The passive resistance value includes a factor of safety equal to 3 in order to reduce the amount of movement necessary to generate passive resistance. The friction cce�cient for foodngs cast direcdy on undisturbed, unweathered, dense to very dense lodgement till may be taken as 035. This value includes a safety factor of 2.0. 13.0 FLOOR SUPPORT As previously discussed, substantial thicknesses of uncontrolled fill and loose, natural sediments underlie d�e area of the proposed building. Several options are available for providing support for the proposed slab-on-grade garage and basement floors. Options 1 and 2 fully mitigate the potential For total and differential settlements caused by the uncontrolled fill soils underlying the site. Option 3 will provide some partial mitigation but the owner should expect cracking and possible differential slab movement. In order to limit transfer of moisture through the floors, all floors should be cast atop a minimum of 4 inches of washed pea gravel to act as a capillary break. It should also be protected from dampness by an impervious 6-mil or thicker plastic moismre barrier placed orer the capillary break material. In addition, it is recommended that 2 inches of clean sand cover be placed o,�er the moisture barrier to protect the intcgTiry of the barrier during concrete � placement and to aid in the curing of the concrete. O tion 1: Excavation and Re lacement of Existin Fill 5oils and Loose Natural Sediments A slab-on-grade floor could be supported on structural fill placed direcdy atop medium dense to very dense, natural, lodgement till sediments. For this option, we recommend that all the existing fill soils and loose, nacural sediments be overexcavated from below the area of the proposed building. Exposed soil should then be recompacted to at least 90 percent of the modified Proctor maximum densiry (ASTM:D 1557). Struc[ural fill should then be placed as described in the Structura! Fill section of this report to attain the desired floor subgrade elevation. Altematively, if desired floor subgrade elevations can be attained without placing structural fill, the capillary break material and floor slab may be placed direcdy over the recompacted, natural, lodgement till sediments. 13