with no fine particles. The surface of the backfill is treated

was further assumed that the pile heads were free to rotate.

to facilitate a runoff, and weep holes are provided so that

As noted earlier, the factor of safety must be in the loading.

water will not collect behind the wall. The forces P1 , P2 ,

Therefore, the loadings shown in Table 5-3 were used in the

Ps , and wP (shown in Figure 5-6) were computed as

preliminary computations. Table 5-4 shows the movements

follows: 21.4, 4.6, 18.4, and 22.5 kips, respectively. The

of the origin of the global coordinate system when

resolution of the loads at the origin of the global coordinate

equation 5-19 through 5-21 were solved simultaneously.

system resulted in the following service loads: *P*v = 46 kips,

The loadings were such that the pile response was almost

linear so that only a small number of iterations were

done). The moment of inertia of the gross section of the pile

was used in the analysis. The flexural rigidity *EI *of the piles

was computed to be 5.56 109 pounds per square inch.

Computer Program PMEIX was run and an interaction

diagram for the pile was obtained. That diagram is shown

in Figure 5-7. A field load test was performed at the site

and the ultimate axial capacity of a pile was found to be 176

kips. An analysis was made to develop a curve showing

axial load versus settlement. The curve is shown in

Figure 5-8. The subsurface soils at the site

required to achieve converenge. The computed pile-head

movements, loads, and moments are shown in Table 5-5.

(6) Verify results. The computed loading on the piles is

shown in Figure 5-9 for Case 4. The following check is

made to see that the equilibrium equations are satisfied.

E Fv ' 24.2 % 97.2 cos 14 &14.3 sin 14

consist of silty clay. The water content averaged 20 percent

' 24.2 % 94.3 & 3.5 ' 115.0 kips OK

in the top 10 feet and averaged 44 percent below 10 feet.

The water table was reported to be at a depth of 10 feet

EFh ' 15.2 % 14.3 cos 14 % 97.2 sin 14

from the soil surface. There was a considerable range in the

' 15.2 % 13.9 % 23.6 ' 52.7 kips OK

undrained shear strength of the clay and an average value of

3 kips per square foot was used in the analysis. A value of

EM ' & ( 24.2 ) ( 1.5 ) % ( 97.2 cos 14 ) ( 1.5 )

the submerged unit weight of 46 pounds per cubic foot as

& ( 14.3 sin 14 ) ( 1.5 )

employed and the value of g50 was estimated to be 0.005. In

' & 36.3 % 141.4 & 5.2

making the computations, the assumption was made that all

of the load was carried by piles with none of the load taken

' 99.9 ft&kips OK

by passive earth pressure or by the base of the footing. It

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