Consider a 500 mm diameter pile having a length of 18 m in a clay. Given: γ = 20.0 kN/m³ and c_u = 60 kN/m².

a. Determine the maximum allowable load (Qall) with FS = 3. Use the a method and Table 12.11 for determining the skin friction and Eq. (12.20) for determining the point load. Allow a factor of safety of 3.

b. What percentage of the ultimate load is being carried by the pile shaft? Is it a friction pile?

Table 12.11

Variation of a (Interpolated

Values Based on

Terzaghi et al., 1996)

c_u/p_a ……………………………. α

≤ 0.1 ………………………….. 1.00

0.2 ………………………….. 0.92

0.3 ………………………….. 0.82

0.4 ………………………….. 0.74

0.6 ………………………….. 0.62

0.8 ………………………….. 0.54

1.0 ………………………….. 0.48

1.2 ………………………….. 0.42

1.4 ………………………….. 0.40

1.6 ………………………….. 0.38

1.8 ………………………….. 0.36

2.0 ………………………….. 0.35

2.4 ………………………….. 0.34

2.8 ………………………….. 0.34

Note: p_a = atmospheric pressure ≈ 100 kN/m²

Eq. (12.20)

Transcribed Image Text:

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