B. METHOD OF REPRESENTING TRAFFIC LIVE LOADS

or triaxial tests (ASTM D 2850). The unit weight,

three locations along the wall are checked to

, will be determined in a moisture density test

determine the most critical.

(ASTM D 698). Generally, 95 percent of ASTM D

698 maximum density can be easily attained with

sure and live load pressure diagrams are combined

granular materials. However, other densities can

to develop the composite diagram used for design

be specified so long as the friction angle used is

as shown in Figure 7-1b.

consistent with that density. The saturated unit

weight is used in lateral pressure calculations.

mine the vertical strength of the fabric layer, the

fabric allowable tensile strength, S , is set equal to

properties of the retained soil, calculate the pres-

the lateral force calculated from

, where

is

sure coefficient,

The lateral earth

the lateral pressure at the middle of the layer.

pressure expression:

Thus, knowing the fabric tensile strength, and

value of

the fabric vertical spacing, X , can be

calculated. The fabric strength should be divided

is used to calculate the triangular shaped pressure

by the appropriate safety factor. The equation for

distribution curve for the height of retaining wall

fabric spacing is:

desired.

(eq 7-6)

first necessary to determine the design load. Lat-

eral pressure diagrams must be developed for each

vehicle or other equipment expected to apply loads

to the retaining wall using equation 7-3. The

, is used to solve for the pullout

equation is solved for each wheel and the results

resistance which can be developed at a given depth

added to obtain the lateral pressure. This pressure

geotextile length combination or to solve for d ,

is calculated at 2-foot vertical intervals over the

the depth required to develop

. The usual case

height of the retaining wall. Normally, from one to

for walls is to set

equal to the geotextile

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