313 76TH ST SE WESTERN WIRELESS CORPORATION Geotech Report 2018-01-02 MF Import

ADaPT Engineering, Inc. Western Wireless Corporation ADaPTJob No, WA98.993 April 1, 1998 Page 7 a: T- /E�` Il nn 11 where E = modulus of elasticity(psi) 1 = moment of inertia(ins) nh=constant of horizontal subgradc reaction(pci) The factors E and I are governed by the internal material strength characteristics of the pier. A representative value of nh for the soil types encountered at this site is presented below in Table A. Piers with a UT ratio of less than 2 may be assumed to be relatively rigid and acting as a pole. the passive pressure approach may be used for this condition. For piers with a Uf ratio greater than 2, the modulus of subgradc reaction method is typically used. Both of these methods are discussed below: Passive Pressure Method: The passive pressure approach is conservative by neglecting the redistribution of vertical stresses and shear forces that develop near the bottom of the pier and contribute to resisting lateral loads. We recommend using the allowable passive rarth pressure (expressed as equivalent fluid unit weights) listed in Table 3. Table 3 Allowable Passive Pressures Depth(feet) Allowable Passive Pressure(pcf) 0-2 0 2-10 250 10-30 350 The allowable passive earth pressure presented in Table 3 may be assumed to be acting over an arca measuring 2 pier diameters in width by 8 pier diameters in depth, neglecting the uppermost 2 feet of embedment below the ground surface. According to the NAVFAC Design Manual 7.2, a lateral deflection equal to about 0.01 times the pier length would be required lo mobilize the allowable passive pressure presented above. Higher deflections would ;nobilize higher passive pressures. When developing the allowable passive pressure listed in Table 3, we have incorporated a safety factor of at least 1.5, which is commonly applied to transient or seismic loading conditions.