729 100TH ST SE Geotech Report 2018-01-02 MF Import

. � .VID L. NELSON AND ASSJLIATES, INC. � . Crmsuhing Engineering GeoloQy April 7, 1989 Pro�ect No. 3989 Page 7 foot may be used. To develop the "ective" pressure conditton, the Na11 must be allowed to yield about tts base a distance on the order of 0.001 times its total hetght. The effect of surcherges, such as traffic or floor loads, should also be considered. For a uniformly dTstributed load behind the wall , e corresponding uniformly distributed pressure equal to 30 percent or 5U percent of the surcharge should be added to the lateral soil pressure for yielding and non- ytelding walls, respectively. If filling beM nd the wa11 1s performed, I � compaction oi beckfill within one-half of the wall embedment height behind the I wall should be performed with light equipment such that the wall 1s not adverSely stressed. . Lateral earth pressures acting on foundatlon wa11s could be �resisted 1n the � prepared structural f111 soils by use of foundatlon base friction. A base friction coefficient of 0.5 is considered appropriate for the enticlpated . foundation soils. The use of passlve earth pressure to develop additional reslstance to iateral pressures should be made only after a review of the � final site grade and slope conflguratlon by this office. An appropriate factor of safety should be applied to the ahove Dase friction valu, to resist � sliding. � The above values essume the presence of the sotls encountered in our � explorattons, and a free-drolning materiel behind the subgrade wali . These values do not take into account hydrostatic pressures, sloping ground behind � the wall , or surcharges due tto equ{pment or ed�acent structural loads. These values further assume the use of an effective drein system elong the backslde � of the wall . Me suggest the use of a free-dralning coerse sand end ffne gravel backfill aiong the backside of the wall to reduce pressures on walls � and to reduce potential for molsture problems. This materlal should conform to the gradation as descrlbed 1n the following taDle: � �