Transmission And Substation Foundations - Technical Design Manual (TD06088E)

For granular soil (sand):

ρ H 2

Equation 4-51

P a = ½K a

фρ H 2

Equation 4-52

P p = ½K p

For cohesive soil (clay):

P a = ½K a rH 2 – 2cH + 2c 2 / фρ

Equation 4-53

ρ H 2 + 2cH

Equation 4-54

P p = ½K p

where:

K 0 = Coefficient of earth pressure at rest K a = Coefficient of active earth pressure K p = Coefficient of passive earth pressure H = Height of wall or resisting element c = Cohesion ф ’ = Effective stress friction angle of soil P a = Active earth pressure ρ = Unit weight of soil

Equations 4-48 through 4-54 are from NAVFAC Design Manual DM7, Foundations and Earth Structures (see References at the end of this section).

Table 4-15 is a tabulation of the coefficient for at rest, active, and passive earth pressure for various soil types, relative densities and consistencies. TABLE 4-15 COEFFICIENTS OF EARTH PRESSURE (DAS, 1987) Soil K 0 , Drained K 0 , Total K a , Total K p , Total Clay, soft * 0.6 1 1 1 Clay, hard * 0.5 0.8 1 1 Sand, loose 0.6 0.53 0.2 3 Sand, dense 0.4 0.35 0.3 4.6 * Assume saturated clays

DESIGN METHODOLOGY

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