For the problem given in Ex. 17.1, determine the allowable load for a settlement of 10 mm \left(=S_{a}\right). All the other data remain the same.
For the problem given in Ex. 17.1, determine the allowable load for a settlement of 10 mm \left(=S_{a}\right). All the other data remain the same.
Allowable skin load
Settlement ratio S_{R}=\frac{S_{a}}{d}=\frac{10}{1.5 \times 10^{3}} \times 100=0.67 \%
From Fig. 17.18 for S_{R}=0.67 \%, N_{f m}=\frac{Q_{f m}}{Q_{f}}=0.95 by using the trend line.
Q_{f m}=0.95 Q_{f}=0.95 \times 8,549=8,122 kN.
Allowable base load for S_{a}=10 mm
From Fig. 17.19 for S_{R}=0.67 \%, N_{b m}=\frac{Q_{b m}}{Q_{b}}=0.4
Q_{b m}=0.4 Q_{b}=0.4 \times 2,384=954 kN.
Now the allowable load Q_{a s} based on settlement consideration is
Q_{a s}=Q_{f m}+Q_{b m}=8,122+954=9,076 kN
Q_{a s} based on settlement consideration is very much higher than Q_{a} (Ex. 17.1) and as such Q_{a} governs the criteria for design.