Question 17.4: For the problem given in Ex. 17.3, determine the allowable l...

Skin load Q_{f m} (mobilized)

Settlement ratio S_{R}=\frac{10}{1.5 \times 10^{3}} \times 100=0.67 \%

From Fig. 17.18 for S_{R}=0.67, N_{f m}=0.95 from the trend line.

Therefore Q_{f m}=0.95 \times 5,375=5,106 kN

Base load Q_{b m} (mobilized)

From Fig. 17.19 for S_{R}=0.33 \%, N_{b m}=0.3 from the trend line.

Hence Q_{b m}=0.3 \times 12,717=3815 kN

The factor of safety with respect to Q_{u} is (from Ex. 17.3)

This is low as compared to the normally accepted value of F_{s}=2.5 . \text { Hence } Q_{a} rules the design.