A 7-m-deep braced cut in sand is shown in Figure 14.13. In the plan, the struts are placed at s = 2 m center to center. Using Peck’s empirical pressure diagram, calculate the design strut loads.

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Refer to Figure 14.11a. For the lateral earth pressure diagram,
[latex]\sigma_a=0.65\gamma H an^2 \left(45-\frac{\phi^\prime}{2} ight)=(0.65)(16)(7) an^2 \left(45-\frac{30}{2} ight)=24.27[/latex] kN/m²
Assume that the sheeting is hinged at strut level B. Now refer to the diagram in Figure 14.14 We need to find reactions at A, [latex]B_1, B_2,[/latex] and C. Taking the moment about [latex]B_1[/latex], we have
[latex]2A=(24.27)(3)\left(\frac{3}{2} ight); A=54.61[/latex] kN/m
Hence,
[latex]B_1 = (24.27)(3) - 54.61 = 18.2 [/latex] kN/m
Again, taking the moment about [latex]B_2[/latex], we have
[latex]2C=(24.27)(4)\left(\frac{4}{2} ight)\C=97.08[/latex] kN/m
So
[latex]B_2 = (24.27)(4) - 97.08 = 0[/latex]
The strut loads are as follows:
At level A: (A)(s) = (54.61)(2) = 109.22 kN
At level B: [latex](B_1+B_2)(s)[/latex]= (18.2 + 0)(2) = 36.4 kN
At level C: (C)(s) = (97.08)(2) = 194.16 kN

Question 14.2: A 7-m-deep braced cut in sand is shown in Figure 14.13. In t...

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