The question asks for the maximum permissible depth of a vertical excavation in clayey soil. We are given:
The goal is to find the maximum depth ($H$) for stability.
For a vertical cut in clayey soil, the relationship between cohesion, unit weight, depth, and stability number is given by:
$c = S_n \times \gamma \times H$To find the maximum depth ($H$), we rearrange the formula:
$H = \frac{c}{S_n \times \gamma}$Now, substitute the given values:
$H = \frac{100 \text{ kN/m}^2}{0.3 \times 15 \text{ kN/m}^3}$ $H = \frac{100}{4.5} \text{ m}$ $H \approx 22.22 \text{ m}$The maximum depth of excavation for the vertical face to remain stable is approximately $22.22 \text{ m}$.