Determine the maximum load that can be allowed on the 450 mm diameter pile shown in Figure P12.9, with a factor of safety of 3. Use the a method and Table 12.11 for determining the skin friction and Eq. (12.20) for determining the point load.

Figure P12.9

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)

Clay y = 18.0 kN/m3 C= 40 kN/m2 5 m Clay y = 18.5 kN/m C = 60 kN/m2 6 m %3D 8 m Clay y = 19.0 kN/m3 Cy = 80 kN/m2