4501 COLBY AVE 2016-01-01 MF Import

GeoTest Services, Inc. January 5.2�707 4501 Colby Avenue, Everett,WA Job No. 07-0028 I Foundation walla, Retaining walis and Lateral earth pressure The lateral earth pressures that develop against subsurface building and retaining walls wiil depend on the method of backfill placement, degree of compaction, slope of backfill, I type of backfill material, provisions for drainage. magnitude and location of any adjacent I surcharge loads, and the degree fo which the wall can yield laterally during or after placement of backfill. If the wall is allowed to rotate or yield so the top of the wall moves an amount equal to or greater than about 0.001 times its height (a yielding walq, the soil pressure exerted wili be the active soil �ressure. When a subsurface wall is restrained against lateral movement or tilting (a nonyielding wall), the soil pressure exerted is the , at-rest soil pressure. Wail restraint may develop if a rigid structural network is constructed prior to backfillinQ or the wall is inherently s:iff. For non-yielding walls such as foundation walls with level backfill under drained conditions, use the following design data: Maximum soil density (gravel soii assumed) = 135 Iblft' Coefficient of At-Rest Earth Pressure !Co = 0.41 At-Rest Earlh Pressure eSuivalent fluid density = 55 Ib/ft' For yieiding walls such as earth retaining walis with level backfiil under drained conditions use the following design data: Maximum soil density(gravel soil assumed) = 135 IbIH' Coe�cient of A�tive Earih Pressure K, = 0.26 Active earth pressure equivalent fluid density = 35 Ib/ft' Design of subsurface walls should include approp�iate lateral pressures caused by surcharge loads localed within a horizontal distance equal to or less than the height of the wail. For uniform surcharge pressures, a uniformty distributed lateral pressure equal to 35 percent and 50 percent of the vertical surcharge pressure should be added to the lateral soil pressures for yielding and nonyielding walls, respectively. Passive earth pressures developed against ihe sides of building foundations, in conjunclion with friction developed between the base of the footings and the supporting subgrade, will resist lateral loads traiismitted from the struciure to its foundation. For passive resistance oi foundation wails against well-compacted fill under drained conditions, use the following design data: Maximum soil density (gravel soil assumed) = 135 Iblft' Coefficient of Passive Earth Pressure KP = 3.69 Passive earth pressure equivalent fluid density = 300 Iblft' Coefficient of Lateral Sliding = 0.35 Page 3 of 5 �i/ (�. %�