Chapter 17 Soil-Bearing Capacity for a Shallow Foundation

Chapter 17

17.1 Shelby tube A:
Do2 − Di2 (76.2) 2 − (73) 2
Eq. (17.6): AR (%) = (100) = × 100 = 8.96% ≤ 10%
Di2 (73) 2
Samples can be considered undisturbed. Suitable for grain size distribution,
Atterberg limits, consolidation and unconfined compression tests.

Shelby tube B:
Do2 − Di2 (3.5) 2 − (3.375) 2
Eq. (17.6): AR (%) = (100) = × 100 = 7.54% ≤ 10%
Di2 (3.375) 2
Samples can be considered undisturbed. Suitable for grain size distribution,
Atterberg limits, consolidation and unconfined compression tests.

Split spoon sampler:
Do2 − Di2 (50.8) 2 − (35) 2
Eq. (17.6): AR (%) = (100) = × 100 = 110% ≥ 10%
Di2 (35) 2
Samples can be considered as highly disturbed. Suitable for grain size distribution
and Atterberg limits tests, but not for consolidation and unconfined compression
tests.


17.2 −0.5
σ 0′ ⎡σ ′ ⎤
Depth CN = ⎢ 0 ⎥ N60 (N1)60 = CN N60
(m) (kN/m2) ⎣ pa ⎦
2 34 1.71 7 ≈12
4 68 1.21 10 ≈12
6 102 0.99 11 ≈11
8 136 0.857 14 ≈12
10 170 0.767 9 ≈7


⎡ ⎤
⎢ ⎥
φ ′ = tan −1 ⎢ ⎥ ; pa ≈ 100 kN/m2
N 60
17.3
⎢ ⎛ σ o′ ⎞ ⎥
⎢12.2 + 20.3⎜⎜ p ⎟⎟ ⎥
⎣⎢ ⎝ a ⎠ ⎦⎥
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