Question 6.10: A raft foundation of the size given in Fig. Ex. 6.10 carries...

The depth at which \sigma_{z} required is 9 m.

Using Fig. 6.12, the scale of the foundation plan is AB = 3 cm = 9 m or 1 cm = 3 m. The foundation plan is required to be made to a scale of 1 cm = 3 m on tracing paper. This plan is superimposed on Fig. 6.12 with O coinciding with the center of the chart. The plan is shown in dotted lines in Fig. 6.12.

Number of loaded blocks occupied by the plan, N = 62

Influence value, C_{i}=0.005, q=300 kN / m ^{2}

The vertical stress, \sigma_{z}=C_{i} N q=0.005 \times 62 \times 300=93 kN / m ^{2}.